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The vascular and perivascular cells, including telocytes (TCs) and immune cells, play an important role in male fertility. The current study intended to describe in detail the microvascular structures harboring special regulatory devices in addition to the interstitial cellular components of the one-humped camel epididymis. The samples were collected from 10 clinically healthy mature camels (Camelus dromedarius). The distribution and characteristics of TCs, peripheral blood vessels of the epididymis, and immune cells were investigated using the light, immunohistochemistry, immunofluorescence, and transmission electron microscopy analyses. Frequent occlusive or throttle arterioles were demonstrated in the epididymal interstitium and their tunica media consisted of glomus cells. In addition, some vein walls consisted of one or two layers of glomus cells. TCs, fibroblasts, muscle cells, and tunica media of the blood vessels, that present in the loose connective tissue surrounding the intertubular interstitium of camel epididymis, showed a positive reaction with vimentin. The endothelium of blood vessels and veins showed positive immunoreactivity for CD34 and vascular endothelial growth factor (VEGF). Furthermore, VEGF, CD34, and S100 proteins were expressed in dendritic cells (DCs) as well as TCs. The current data suggest the involvement of DCs and TCs in angiogenesis and a possible role for the interstitial components in creating an appropriate milieu for the full maturation of sperms.

Background/aims: Cardiovascular complications are responsible for increased mortality and morbidity in chronic kidney disease (CKD) patients. Functional and structural changes of peritoneal membrane are reported in CKD patients both on conservative treatment and on renal replacement therapy (RRT). The aim of the study was to assess the structure of peritoneal membrane small arteries (precapillary arterioles) in diabetic and non-diabetic CKD stage 5 patients before initiation of peritoneal dialysis (PD) and evaluate its relationship with heart and large arteries abnormalities and with selected biochemical parameters., Methods: Evaluation of 42 CKD stage 5 patients before starting PD. Diabetic (n=26) and non-diabetic (n=16) patients were compared. Peritoneal membrane samples were taken during Tenckhoff catheter insertion. Histopathological evaluation of peritoneal precapillary arterioles (arteriolar evaluation) with measurement of wall thickness (WT) and calculation of lumen/vessel (L/V) ratio was performed in each patients. Echocardiography, intima media thickness (IMT), pulse wave velocity (PWV), ambulatory blood pressure monitoring (ABPM) and biochemical parameters assessment: serum albumin (SA), total cholesterol (TCH), hemoglobin (Hgb), parathormone (PTH), serum calcium (Ca), serum phosphorus (P), transferrin saturation (TSAT%), C-reactive protein (CRP) were performed in each participant., Results: There were no statistically significant differences in peritoneal membrane arteriolar indices - wall thickness (WT) and L/V ratio between investigated groups. There was statistically significant higher PWV value in diabetic patients. There were no statistically significant differences in echocardiographic indices, IMT, laboratory data in analyzed groups. There were some linear correlations between: PWV vs IMT (R=0,84; p=0,0006); PWV vs PP (R=0,58; p=0,03) in non-diabetic and linear correlation between: PWV vs age (R=0,75; p=0,02); WT vs DP (R=-0,93; p=0,001); WT vs DBP ( R=0,64; p=0,04) in diabetic group., Conclusion: Peritoneal membrane arteriolar damage seems to be an integrated part of cardiovascular system damage in CKD stage 5 patients., (© 2018 The Author(s). Published by S. Karger AG, Basel.)

Dilatation of periarteriolar spaces in MRI of the ageing human brains occurs in white matter (WM), basal ganglia and midbrain but not in cerebral cortex. Perivenous collagenous occurs in periventricular but not in subcortical WM.Here we test the hypotheses that (a) the capacity for dilatation of periarteriolar spaces correlates with the anatomical distribution of leptomeningeal cells coating intracerebral arteries and (b) the regional development of perivenous collagenous in the WM correlates with the population of intramural cells in the walls of veins.The anatomical distribution of leptomeningeal and intramural cells related to cerebral blood vessels is best documented by electron microscopy, requiring perfusion-fixed tissue not available in human material. We therefore analysed perfusion-fixed brain from a 12-year-old Beagle dog as the canine brain represents the anatomical arrangement in the human brain. Results showed regional variation in the arrangement of leptomeningeal cells around blood vessels. Arterioles are enveloped by one complete layer of leptomeninges often with a second incomplete layer in the WM. Venules showed incomplete layers of leptomeningeal cells. Intramural cell expression was higher in the post-capillary venules of the subcortical WM when compared with periventricular WM, suggesting that periventricular collagenosis around venules may be due to a lower resistance in the venular walls. It appears that the regional variation in the capacity for dilatation of arteriolar perivascular spaces in the white WM may be related to the number of perivascular leptomeningeal cells surrounding vessels in different areas of the brain., (© 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.)

The impact of disease-related changes in the extracellular matrix (ECM) on the mechanical properties of human resistance arteries largely remains to be established. Resistance arteries from both pig and human parietal pericardium (PRA) display a different ECM microarchitecture compared with frequently used rodent mesenteric arteries. We hypothesized that the biaxial mechanics of PRA mirror pressure-induced changes in the ECM microarchitecture. This was tested using isolated pig PRA as a model system, integrating vital imaging, pressure myography, and mathematical modeling. Collagenase and elastase digestions were applied to evaluate the load-bearing roles of collagen and elastin, respectively. The incremental elastic modulus linearly related to the straightness of adventitial collagen fibers circumferentially and longitudinally (both R 2 ≥ 0.99), whereas there was a nonlinear relationship to the internal elastic lamina elastin fiber branching angles. Mathematical modeling suggested a collagen recruitment strain (means ± SE) of 1.1 ± 0.2 circumferentially and 0.20 ± 0.01 longitudinally, corresponding to a pressure of ~40 mmHg, a finding supported by the vital imaging. The integrated method was tested on human PRA to confirm its validity. These showed limited circumferential distensibility and elongation and a collagen recruitment strain of 0.8 ± 0.1 circumferentially and 0.06 ± 0.02 longitudinally, reached at a distending pressure below 20 mmHg. This was confirmed by vital imaging showing negligible microarchitectural changes of elastin and collagen upon pressurization. In conclusion, we show here, for the first time in resistance arteries, a quantitative relationship between pressure-induced changes in the extracellular matrix and the arterial wall mechanics. The strength of the integrated methods invites for future detailed studies of microvascular pathologies. NEW & NOTEWORTHY This is the first study to quantitatively relate pressure-induced microstructural changes in resistance arteries to the mechanics of their wall. Principal findings using a pig model system were confirmed in human arteries. The combined methods provide a strong tool for future hypothesis-driven studies of microvascular pathologies., (Copyright © 2017 the American Physiological Society.)

Objective: The microvasculature of the CAM in the developing chick embryo is characterized by interdigitating arteriolar and venular trees, connected at multiple points along their lengths to a mesh-like capillary plexus. Theoretical modeling techniques were employed to investigate the resulting hemodynamic characteristics of the CAM., Methods: Based on previously obtained anatomical data, a model was developed in which the capillary plexus was treated as a porous medium. Supply of blood from arterioles and drainage into venules were represented by distributions of flow sources and sinks. Predicted flow velocities were compared with measurements in arterioles and venules obtained via video microscopy., Results: If it was assumed that blood flowed into and out of the capillary plexus only at the ends of terminal arterioles and venules, the predicted velocities increased with decreasing diameter in vessels below 50 μm in diameter, contrary to the observations. Distributing sources/sinks along arterioles/venules led to velocities consistent with the data., Conclusions: These results imply that connections to the capillary plexus distributed along the arterioles and venules strongly affect the hemodynamic characteristics of the CAM. The theoretical model provides a basis for quantitative simulations of structural adaptation in CAM networks in response to hemodynamic stimuli., (© 2016 John Wiley & Sons Ltd.)

Renin immunoreactivity was localized at the light and electron microscopic level in two elasmobranch fish species, the Atlantic stingray, Dasyatis sabina, and river ray, Potamotrygon humerosa. At the light microscopic level, the peroxidase-anti-peroxidase method showed a positive immunoreactivity in modified smooth muscle cells in kidney afferent arterioles as well as in arterioles of several organs: rectal gland, inter-renal gland, conus arteriosus, and gill. Electron microscopic renin-positive immunogold localization was confined to the contents of membrane bound granules in the modified smooth muscle cells of these arterioles. The presence of renin-containing granules in the modified smooth muscle, "granular cells," of the renal glomerular afferent arteriole of these two stingray species adds support to earlier studies which showed the structural components of a complete juxtaglomerular apparatus and some of the biochemical and molecular components of a renin-angiotensin system (RAS) as found in teleost fish, reptiles, birds, and mammals. A notable result, however, was the renin-positive immunoreaction in the arteriolar wall of all other organs studied here. The presence of this "diffuse renin system" in the connective tissue of various organs suggests that in these two stingray species in addition to local organ-specific functions, the RAS may act as a systemic mechanism to regulate blood pressure and blood flow in the body.

Tissue repair processes are characterized by the biphasic recruitment of distinct subpopulations of blood monocytes, including classical ("inflammatory") monocytes (IMs, Ly6C(hi)Gr1(+)CX3CR1(lo)) and non-classical anti-inflammatory monocytes (AMs, Ly6C(lo)Gr1(-)CX3CR1(hi)). Drug-eluting biomaterial implants can be used to tune the endogenous repair process by the preferential recruitment of pro-regenerative cells. To enhance recruitment of AMs during inflammatory injury, a novel N-desulfated heparin-containing poly(ethylene glycol) diacrylate (PEG-DA) hydrogel was engineered to deliver exogenous stromal derived factor-1α (SDF-1α), utilizing the natural capacity of heparin to sequester and release growth factors. SDF-1α released from the hydrogels maintained its bioactivity and stimulated chemotaxis of bone marrow cells in vitro. Intravital microscopy and flow cytometry demonstrated that SDF-1α hydrogels implanted in a murine dorsal skinfold window chamber promoted spatially-localized recruitment of AMs relative to unloaded internal control hydrogels. SDF-1α delivery stimulated arteriolar remodeling that was correlated with AM enrichment in the injury niche. SDF-1α, but not unloaded control hydrogels, supported sustained arteriogenesis and microvascular network growth through 7 days. The recruitment of AMs correlated with parameters of vascular remodeling suggesting that tuning the innate immune response by biomaterial SDF-1α release is a promising strategy for promoting vascular remodeling in a spatially controlled manner., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: In hypertension, changes in small arterial structure are characterized by an increased wall-to-lumen ratio (WLR). These adaptive processes are modulated by the rennin-angiotensin system. It is unclear whether direct renin inhibitors exert protective effects on small arteries in hypertensive patients., Methods: In this double-blind, randomized, placebo-controlled study (http://www.clinicaltrials.gov: NCT01318395), 114 patients with primary hypertension were randomized to additional therapy with either placebo or aliskiren 300 mg for 8 weeks after 4 weeks of standardized open-label treatment with valsartan 320 mg (run-in phase). Parameter of arteriolar remodelling was WLR of retinal arterioles (80 - 140 μm) assessed noninvasively and in vivo by scanning laser Doppler flowmetry (Heidelberg Engineering, Germany). In addition, pulse wave analysis (SphygmoCor, AtCor Medical, Australia) and pulse pressure (PP) amplification were determined., Results: In the whole study population, no clear effect of additional therapy with aliskiren on vascular parameters was documented. When analyses were restricted to patients with vascular remodelling, defined by a median of WLR more than 0.3326 (n = 57), WLR was reduced after 8 weeks by the treatment with aliskiren compared with placebo (-0.044 ± 0.07 versus 0.0043 ± 0.07, P = 0.015). Consistently, after 8 weeks of on-top treatment with aliskiren, there was an improvement of PP amplification compared with placebo (0.025 ± 0.07 versus -0.034 ± 0.08, P = 0.013), indicative of less stiff arteries in the peripheral circulation., Conclusion: Thus, our data indicate that treatment with aliskiren, given on top of valsartan therapy, improves altered vascular remodelling in hypertensive patients.

The aim of the present study was to investigate the extensive invasion of tumor cells into normal brain tissue, a life‑threatening feature of malignant gliomas. How invasive tumor cells migrate into normal brain tissue and form a secondary tumor structure remains to be elucidated. In the present study, the morphological and phenotypic changes of glioma cells during invasion in a C6 glioma model were investigated. C6 glioma cells were stereotactically injected into the right putamen region of adult Sprague‑Dawley rats. The brain tissue sections were then subjected to hematoxylin and eosin, immunohistochemical or immunofluorescent staining. High magnification views of the tissue sections revealed that C6 cells formed tumor spheroids following implantation and marked invasion was observed shortly after spheroid formation. In the later stages of invasion, certain tumor cells invaded the perivascular space and formed small tumor clusters. These small tumor clusters exhibited certain common features, including tumor cell multilayers surrounding an arteriole, which occurred up to several millimeters away from the primary tumor mass; a high proliferation rate; and similar gene expression profiles to the primary tumor. In conclusion, the present study revealed that invading tumor cells are capable of forming highly proliferative cell clusters along arterioles near the tumor margin, which may be a possible cause of the recurrence of malignant glioma.

Objective: To estimate the number of L-type calcium (Ca2+) channels in the afferent and efferent arteriolar renin-positive and renin-negative smooth muscle cells and endothelial cells of the kidney arterioles in order to seek a relationship between the cell functions and the number of ion channels in the cell membranes., Study Design: In diabetes the main source of renin/prorenin is the tubules, while the renin granulation of the afferent arterioles is increased relative to the normal. The release of renin is related to the Ca2+ levels of the intracellular and extracellular spaces of the afferent arterioles. The L-type calcium channel blockers have a stimulatory effect on the renin system. The immunohistochemical signal of the antibody against the L-type Ca2+ channels was estimated stereologically., Results: In the diabetic kidney the relative number of L-type Ca2+ channels on the surface of the renin-positive cells of the afferent arterioles was significantly increased. In the normal kidney there was a difference in the relative number of L-type Ca2+ channels on the surface of the endothelial cells between the renin-positive and renin-negative profiles of the afferent arterioles., Conclusion: The increment in the number of Ca2+ channels on the renin-positive cell surface in the diabetic kidney could be related to the high renin granularity of the afferent arterioles. In the normal kidney the differences in the number of L-type Ca2+ channels on the endothelial cell surface may play a role in the higher permeability of the renin-positive part of the afferent arterioles.

The axial blood velocity (Vax) association with microvessel diameter (D) was studied at 104 different postcapillary venules (4 μm <  D <  24 μm) and 30 different precapillary arterioles (6 μm≤D≤12 μm) in the human conjunctiva of normal healthy humans. Venular diameter sizes were classified as "very small" (Group 1, 4.4 μm≤D <  8.9 μm), "small" (Group 2, 8.9 μm≤D <  13.8 μm), "medium" (Group 3, 13.8 μm≤D <  19.1 μm) and "large" (Group 4, 19.1 μm≤D≤23.5). The Spearman's correlation coefficient (rs) in all 4 venular groups was less than 0.36 and not statistically significant (n = 26, p≥0.08). Similar correlation results were observed for the arteriolar group (rs) ≈ 0) for the peak systolic, the average and the end systolic axial velocities. Vax was significantly (p <  0.001) lower in Group 1 in comparison to that in Group 2 and significantly (p <  0.01) lower in Group 2 in comparison to that in Group 3. However, Vax was not significantly lower in Group 3 in comparison to that in Group 4. Average Vax and standard deviation was 0.48 ± 0.13, 0.64 ± 0.16, 0.82 ± 0.25 and 0.88 ± 0.32 mm/s for Groups 1, 2, 3 and 4 respectively. The above results reinforce the importance of measuring D in microvascular hemodynamics. Higher diameters suggest higher axial velocities but Vax does not change significantly within the limits of each of the aforementioned groups.

Introduction: Our previous study of angiotensin II receptor blocker (ARB) administration in rats induced unusual proliferative changes of smooth muscle cells in renal arteriolar walls. The present study examined if the incidence of the changes depended on the rats' age, and how long it would take to find changes., Materials and Methods: Six-week-old (juvenile spontaneous hypertensive rats (SHRs)+ARB group, n=15) and 20-week-old (adult SHRs+ARB group, n=10) male SHRs were fed a standard diet (0.4% NaCl) containing valsartan (10 mg/kg/day; Novartis Co.). Fifteen age-matched SHRs were studied as controls. After 4, 8, and 12 weeks, the rat kidneys were examined under light and electron microscopes and through immunohistochemical studies., Results: Extremely concentric proliferative changes in afferent arteriolar walls were frequently observed in the juvenile SHR+ARB group compared to the adult SHR+ARB group (48.7±6.8% vs 19.3±6.9%; p=0.0307) at the 12(th) week. Increased renin expression and arteriolar changes were found from the 4(th) week in the juvenile SHR+ARB group., Conclusion: This study indicates that ARB administration induces unusual proliferative changes and a marked renin-producing cell increase in afferent arterioles more frequently in juveniles than adult rats. It is suggested that the treatment of ARB in juveniles might have a higher risk of changes in renal afferent arterioles., (© The Author(s) 2013.)

The evaluation of microvascular structure is, in general, not an easy task. Among the methods that may be applied to humans, plethysmographic evaluation of small arteries and wire or pressure micromyography were extensively used in the last decades. The media-to-lumen ratio of small arteries evaluated by micromyography was demonstrated to possess a strong prognostic significance; however, its extensive evaluation is limited by the local invasiveness of the assessment. Noninvasive approaches were then proposed, including capillaroscopy, which provides information about microvascular rarefaction. Recently, the interest of investigators was focused on the retinal microvascular bed. In particular, a noninvasive measurement of the wall-to-lumen ratio of retinal arterioles using scanning laser Doppler flowmetry has been introduced.Recent data suggest a rather good agreement between this approach and micromyographic measurements, generally considered the gold standard approach. Therefore, the evaluation of microvascular structure is progressively moving from bench to bedside, and it could represent, in the immediate future, an evaluation to be performed in all hypertensive patients, in order to obtain a better stratification of cardiovascular risk.

Objective: Microvascular mechanisms are increasingly recognized as being involved in a significant proportion of coronary artery disease (CAD) cases, but their exact contribution or role is unclear. We aimed to define the association between retinal microvascular signs and both CAD extent and severity., Methods: 1120 participants of the Australian Heart Eye Study were included. Retinal vessel caliber was measured from digital retinal images. Extent and severity of CAD was assessed using several approaches. First, a simple scoring classifying participants as having one-vessel, two-vessel, and three-vessel disease was used. Gensini and Extent scores were calculated using angiography findings., Results: After multivariable adjustment, significantly narrower retinal arteriolar caliber in women (comparing lowest versus highest quartile or reference) and wider venular caliber in men (comparing highest versus lowest quartile or reference) were associated with 2-fold and 54% higher odds of having at least one stenosis ≥50% in the epicardial coronary arteries, respectively. Women in the third versus first tertile of retinal venular caliber had 92% and ∼2-fold higher likelihood of having higher Gensini and Extent scores, respectively. Women in the lowest versus highest tertile of retinal arteriolar caliber had greater odds of having higher Extent scores, OR 2.99 (95% CI 1.45-6.16). In men, non-significant associations were observed between retinal vascular caliber and Gensini and Extent scores., Conclusions: An unhealthy retinal microvascular profile, namely, narrower retinal arterioles and wider venules was associated with more diffuse and severe CAD among women., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

The microvasculature of human spleens is still incompletely understood. Two enigmatic types of red pulp microvessels, penicillar arterioles and sheathed capillaries, have already been described in the nineteenth century without gaining much attention afterwards. We performed a detailed analysis of sheathed capillaries to clarify the cellular composition of their sheaths by immunohistological double-staining experiments. Capillary sheaths comprise three different cell types, namely specialized cuboidal CD271(++) inner sheath cells surrounded by CD271(-) macrophages and accumulations of B lymphocytes. The CD271(++) inner sheath cells express the chemokine CXCL13 in a unique single dot pattern. Sheath-associated B lymphocytes consist of IgM(+), IgD(++), and of "switched" cells. T lymphocytes do not accumulate in pericapillary sheaths. The predominant sheath-associated macrophage population is CD163(-)CD68(+) and thus differs from the majority of red pulp macrophages. The sheath-associated macrophages strongly express CD169 only in perifollicular sheaths, but not in sheaths located deeper in the red pulp. IgM(+), IgD(++), and "switched" B cells are also closely associated with red pulp arterioles characterized by the expression of smooth muscle actin in muscle cells and in branched periarteriolar stromal cells. Capillary sheaths are observed in a post-arteriolar position and appear to be of limited length. We suggest to change the term "Vagina periarteriolaris makrophagocytica" of the international histological and embryological terminologies to "Vagina pericapillaris."

Objective: Retinal microvascular signs are markers of cardiovascular disease risk. There are limited data, on relationships between retinal microvascular signs and retinal microvascular endothelial function. We sought to determine the relationship of retinal vascular signs with retinal microvascular endothelial function in patients with or at high risk of coronary artery disease., Methods: Participants with atherosclerosis risk factors and coronary disease (n=258; mean age 57±11 years) were recruited to have static and dynamic retinal vascular assessment. Retinal arteriolar dilatation in response to flicker light (FI-RAD) was measured using the Digital Vessel Analyser and expressed as percentage increase over baseline diameter. Static retinal photographs were acquired utilising a digital fundus camera for measurement of central retinal artery and vein equivalent (CRAE and CRVE), arteriovenous nicking (AVN) and focal arteriolar narrowing (FAN)., Results: Intra-class correlation coefficient was 0.82 for flicker-light induced retinal arteriolar dilatation. There were modest associations in retinal vascular measurements between eyes. For each 10 μm decrease in retinal arteriolar diameter, the absolute increase in FI-RAD was 0.28% (95% CI 0.11, 0.45; p=0.002) independent of age, gender and atherosclerosis risk factors. AVN and FAN were associated with attenuated FI-RAD (β=-0.67%; 95% CI -1.20, -0.15; p=0.012) and (β=-0.83%; 95% CI -1.44, -0.23; p=0.007) respectively after adjustment for age and gender., Conclusion: Assessment of retinal microvascular endothelial function is reproducible and correlated with retinal microvascular structure and signs, independent of atherosclerosis risk factors. Assessment of retinal vascular structure and function may provide insights into atherosclerotic disease., (Crown Copyright © 2014. Published by Elsevier Ireland Ltd. All rights reserved.)

Aim: The aim of this study was to investigate the effects of Rho kinase inhibitor-Fasudil on hypoxic pulmonary hypertension (HPH) and pulmonary vascular remodeling in rats., Materials and Methods: A total of 24 Sprague Dawley rats were evenly randomized into control, model and Fasudil intervention groups. Light and transmission electron microscopy were utilized to observe pulmonary vascular remodeling as well as ultrastructural changes in pulmonary arteriole endothelial cells., Results: The model group showed apparent pulmonary vascular remodeling, pulmonary arteriole endothelial cell injury, the proliferation and swelling of smooth muscle cells around, and the proliferation of collagen fibers. Fasudil intervention improved pulmonary vascular remodeling as well as relieved pulmonary arteriole endothelial cell injury and the proliferation of smooth muscle cells and collagen fibers., Conclusions: Fasudil has preventive and reverse effects on HPH, pulmonary vascular remodeling, and pulmonary arteriole endothelial cell injury.

Recent physiological studies in the kidney proposed the existence of a secondary feedback mechanism termed 'crosstalk' localized after the macula densa. This newly discovered crosstalk contact between the nephron tubule and its own afferent arteriole may potentially revolutionize our understanding of renal vascular resistance and electrolyte regulation. However, the nature of such a crosstalk mechanism is still debated due to a lack of direct and comprehensive morphological evidence. Its exact location along the nephron, its prevalence among the different types of nephrons, and the type of cells involved are yet unknown. To address these issues, computer assisted 3-dimensional nephron tracing was applied in combination with direct immunohistochemistry on plastic sections and electron microscopy. 'Random' contacts in the cortex were identified by the tracing and excluded. We investigated a total of 168 nephrons from all cortical regions. The results demonstrated that the crosstalk contact existed, and that it was only present in certain nephrons (90% of the short-looped and 75% of the long-looped nephrons). The crosstalk contacts always occurred at a specific position--the last 10% of the distal convoluted tubule. Importantly, we demonstrated, for the first time, that the cells found in the tubule wall at the contact site were always type nonA-nonB intercalated cells. In conclusion, the present work confirmed the existence of a post macula densa physical crosstalk contact.

Confocal imaging of Fluo-4, Propidium iodide, and di-8-Anepps loaded ureter were used to study the morphology of terminal arterioles with an inner diameter <50 μm in intact rat ureter. Optical sectioning showed that the muscle coat of the terminal arterioles consisted of a monolayer of highly curved smooth muscle cells which run circumferentially around the endothelium. This technique allowed not only to measure the inner diameter of the terminal arterioles but also to define the orientation and number of revolutions an individual smooth muscle cell made around the endothelium. We measured thickness, width, length, and morphological profile of the myocytes and endothelial cells. Propidium iodide staining showed nuclei of individual cells by continuous imaging at high resolution in serial optical sections. Conventional haematoxylin-eosin, Masson's tri-chrome staining, and transmission electron microscopy were also used in this study to compare the measurements obtained from live confocal imaging with histological standard methods. Parameters obtained from live imaging were significantly different. This technique of live staining allowed measuring the cellular and nuclear dimensions of the terminal arterioles in their natural environment which are important in studying the effects of vascular disease or aging on vascular structure., (Copyright © 2013 Wiley Periodicals, Inc.)

A technique for embedding human undecalcified tooth specimens in Technovit® 9100 was developed, which permits immunohistological evaluation of pulp tissue in serial ground sections. Human molars were divided into 14-18 sections of about 23 µm thickness. Immunohistological double staining for S-100 and CD34 revealed unique associations of myelinated nerve fibre bundles with arterioles, which continued through the entire tooth pulp. These arterioles were not only accompanied by, but partially or totally enveloped in longitudinally orientated myelinated nerve fibre bundles. We speculate that this unique arrangement may mechanically support the arterioles and alleviate detection or regulation of their contraction state by sensory nerve cells., (Copyright © 2013 S. Karger AG, Basel.)

Microcirculatory dysfunction may contribute to delayed cerebral ischemia after subarachnoid hemorrhage (SAH). Using a prechiasmatic injection model, this study investigated ultrastructural changes in microvessels in brain parenchyma to determine the nature of the microthromboemboli, the involvement of nitric oxide (NO) and P-selectin in their formation, and relationship to brain injury after SAH. Brains were examined by electron microscopy (EM) and immunohistochemistry. EM demonstrated that mice with SAH had significantly more arterioles filled with lesions consistent with microthrombi (in cortex, 20 ± 5 for SAH, 8 ± 4 saline-injected and 2.4 ± 0.2 for sham). SAH animals also had more constriction of arterioles. The concentration of NO was lower in mice with SAH (44 ± 9 for sham, 46 ± 20 for saline-injected and 24 ± 11 for SAH). The number of microthrombi correlated with the number of apoptotic neuronal cells (R(2)=0.80 in cortex). Cell membrane P-selectin increased in the endothelium of arterioles in mice with SAH (11.4 ± 0.7 for SAH, 6.8 ± 0.9 for sham and 6.1 ± 0.9 for saline-injected controls). This correlated with decreased NO in the brain. In conclusion, SAH causes microthrombosis and constriction of arterioles, which correlates with neuronal cell death. Increased P-selectin and decreased NO suggest a mechanism for microthrombosis and arteriolar constriction., (Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.)

Background: Microvascular changes have been associated with the metabolic syndrome., Methods: We included 869 participants aged ≥ 40 years from the High-risk for Diabetes Changfeng Study, who had gradable fundus photographs. On digital photographs sum retinal arteriolar and venular calibers were measured with a semi-automated system. Metabolic syndrome was defined according to the International Diabetes Federation consensus., Results: A total of 286 (32.9%) participants was diagnosed with metabolic syndrome. Participants with narrower retinal arteriolar caliber were more often diagnosed with metabolic syndrome (odds ratio 1.78, 95% confidence interval 1.02 – 3.10; lowest vs highest quintile). Additionally adjusting for age, gender, education, smoking and weekly activity, and adding arteriolar and venular caliber simultaneously in the same models did not alter these associations. In the component analyses, participants with narrower retinal arteriolar caliber were more likely to have central obesity, dyslipidaemia or raised blood pressure, and less likely to have raised fasting plasma glucose. The association between wider venular caliber and metabolic syndrome was less pronounced and non-significant (odds ratio 1.34; 95% confidence interval 0.79 – 2.38; highest vs lowest quintile)., Conclusion: Retinal arteriolar narrowing and, to a lesser extent, retinal venular dilatation were associated with metabolic syndrome in this Chinese population. These vascular changes, although small in magnitude, may still be important in the pathophysiological mechanisms involved in the metabolic syndrome.

Blood vessels are highly organized and complex structure, which are far more than simple tubes conducting the blood to almost any tissue of the body. The fine structure of the wall of blood vessels has been studied previously using the electron microscope, but the presence the telocytes associated with vasculature, a specific new cellular entity, has not been studied in depth. Interestingly, telocytes have been recently found in the epicardium, myocardium, endocardium, human term placenta, duodenal lamina propria and pleura. We show the presence of telocytes located on the extracellular matrix of blood vessels (arterioles, venules and capillaries) by immunohistochemistry and transmission electron microscopy. Also, we demonstrated the first evidence of a primary cilium in telocytes. Several functions have been proposed for these cells. Here, the telocyte-blood vessels cell proximity, the relationship between telocytes, exosomes and nervous trunks may have a special significance., (© 2011 The Authors Journal of Cellular and Molecular Medicine © 2011 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd.)

Stroke-prone spontaneously hypertensive rats (SHRSP) are known to show necrosis of the femoral head with a frequency of about 50%. This rat has thus been used as an animal model for necrosis of the femoral head in many studies. In a detailed investigation of feeding vessel disorders that cause femoral head necrosis, we observed changes over time in the feeding vessels using scanning electron microscopy and transmission electron microscopy. In scanning electron microscopy of vascular casts, abnormal findings in feeding vessels of SHRSP with aging from the immature stage included contortion and bending in the lumen with overall narrowing. Under transmission electron microscopy, decreased numbers of smooth muscle cells and increased amounts of collagen fibers were marked, and these changes with hypertrophy of vascular walls might be similar to those of arteriolosclerosis. The structural changes first revealed by transmission electron microscopic observation might cause the friability of the feeding vessels so that contortion and bending occurred, suggesting transient obstruction of blood flow to the femoral head and subsequent induction of femoral head necrosis. These findings should help in understanding the causes of femoral head necrosis in humans, including Perthes' disease.

The relevance of cerebral amyloid angiopathy (CAA) to the pathogenesis of Alzheimer disease (AD) and dementia in general emphasizes the importance of developing novel targeting approaches for detecting and treating cerebrovascular amyloid (CVA) deposits. We developed a nanoparticle-based technology that uses a monoclonal antibody against fibrillar human amyloid-β42 that is surface coated onto a functionalized phospholipid monolayer. We demonstrate that this conjugated nanoparticle binds to CVA deposits in arterioles of AD transgenic mice (Tg2576) after infusion into the external carotid artery using 3 different approaches. The first 2 approaches use a blood vessel enrichment of homogenized brain and a leptomeningeal vessel preparation from thin tangential brain slices from the surface of the cerebral cortex. Targeting of CVA by the antibody-coated nanoparticle was visualized using fluorescent lissamine rhodamine-labeled phospholipids in the nanoparticles, which were compared with fluorescent staining of the endothelial cells and amyloid deposits using confocal laser scanning microscopy. The third approach used high-field strength magnetic resonance imaging of antibody-coated iron oxide nanoparticles after infusion into the external carotid artery. Dark foci of contrast enhancement in cortical arterioles were observed in T2*-weighted images of ex vivo AD mouse brains that correlated histologically with CVA deposits. The targeting ability of these nanoparticles to CVA provides opportunities for the prevention and treatment of CAA.

Purpose: To explore the effects of microbeam radiation (MR) on vascular biology, we used the chick chorioallantoic membrane (CAM) model of an almost pure vascular system with immature vessels (lacking periendothelial coverage) at Day 8 and mature vessels (with coverage) at Day 12 of development., Methods and Materials: CAMs were irradiated with microplanar beams (width, ∼25 μm; interbeam spacing, ∼200 μm) at entrance doses of 200 or 300 Gy and, for comparison, with a broad beam (seamless radiation [SLR]), with entrance doses of 5 to 40 Gy., Results: In vivo monitoring of Day-8 CAM vasculature 6 h after 200 Gy MR revealed a near total destruction of the immature capillary plexus. Conversely, 200 Gy MR barely affected Day-12 CAM mature microvasculature. Morphological evaluation of Day-12 CAMs after the dose was increased to 300 Gy revealed opened interendothelial junctions, which could explain the transient mesenchymal edema immediately after irradiation. Electron micrographs revealed cytoplasmic vacuolization of endothelial cells in the beam path, with disrupted luminal surfaces; often the lumen was engorged with erythrocytes and leukocytes. After 30 min, the capillary plexus adopted a striated metronomic pattern, with alternating destroyed and intact zones, corresponding to the beam and the interbeam paths within the array. SLR at a dose of 10 Gy caused growth retardation, resulting in a remarkable reduction in the vascular endpoint density 24 h postirradiation. A dose of 40 Gy damaged the entire CAM vasculature., Conclusions: The effects of MR are mediated by capillary damage, with tissue injury caused by insufficient blood supply. Vascular toxicity and physiological effects of MR depend on the stage of capillary maturation and appear in the first 15 to 60 min after irradiation. Conversely, the effects of SLR, due to the arrest of cell proliferation, persist for a longer time., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Lipofuscin-like granules, first described by Biava and West in 1965, are a subcellular, quasi-physiologic finding mainly seen in the smooth muscle cells of renal arterioles, but also in juxtaglomerular cells and the lacis cells of human kidneys. They increase in number in subjects affected by arterial hypertension and diabetes. They do not correlate with a specific primary renal disease. Lipofuscin-like granules are not related to renin granules. The world literature on this subject is almost non-existent, and the awareness of this finding or its clinical significance among either pathologists or nephrologists is very poor. We incidentally observed these lipofuscin-like granules in 8 cases during the routine electron microscope examination of 440 renal biopsies, and report herein on their ultrastructural features. Six of these 8 patients were affected by arterial hypertension, one of whom was also concomitantly affected by diabetes mellitus. These lipofuscin-like granules appear as dense bodies with a lipid component, a coarsely granular matrix, and a crystalloid component which may appear in a band or dot pattern, according to the plane of sectioning. The pathologist has to be aware of these lipofuscin-like granules in order not to confuse them with the semicircularly organized (fingerprint) linear immune deposits associated with some specific glomerulopathies., (Copyright © 2010 Elsevier GmbH. All rights reserved.)

Granular osmiophilic material (GOM) is a pathognomonic feature of CADASIL that may be a consequence of pathological processes triggered by Notch3 mutations. Since knowledge of the effects of CADASIL-associated GOM deposits is important to understand the molecular pathogenesis of this disorder, we performed a thorough ultrastructural analysis of GOM morphology in the skin and muscle arterioles in CADASIL patients. Electron microscopy revealed numerous GOM deposits with different morphology including size, shape and osmiophilic density. Osmiophilic granular material of high density was frequently observed in part of GOM deposits located near vascular smooth muscle cells (VSMC) while a part localized distally from the cell body was less dense and loose. On the basis of our observations we postulate that GOM can be formed on the surface of VSMC in the arteriolar wall and penetrate from these cells into the basement membrane and/or extracellular matrix. The dispersion of granules, which form GOM deposits, may be one of the factors triggering the thickening and changes in the basement membrane and/or extracellular matrix.

Spontaneous cerebral artery dissection is a common cause of ischemic stroke in young adults and children. Dissection is often related to arterial wall weakness the cause of which is unknown. An aim of the present paper was to carry out an electron microscopic study of skin arteries and arterioles in patients with ischemic stroke caused by cerebral artery dissection. Skin biopsy samples from 3 patients (2 men and one women, 15, 25 and 43 years of age, respectively) were studied. Electron microscopy revealed changes of endothelial, smooth muscle cells and fibroblasts in the skin microvessels. These changes included the decrease in the number of mitochondria and their alterations (vacuolization, destruction of the cristae, the presence of the needle-shaped crystals and crystal-like inclusions) and swelling of the endoplasmic reticulum. Some of these changes were characteristic of mitochondrial diseases. The changes in the extracellular matrix (thickening of the subendothelial layer and deposition of microcalcificats) were also detected. It is assumed that the mitochondrial cytopathy found in the skin microvessels may be also present in large cerebral arteries. This could underlie dysplastic changes in the cerebral artery wall and predispose to its dissection.

Purpose: To analyze the vasculature and extracellular matrix changes in the prelaminar region (PreLR) of the optic nerve head (ONH) and in the peripapillary sclera of eyes with primary open-angle glaucoma (POAG) and age-matched control eyes., Methods: In histologic sagittal sections of 46 eyes with POAG and 45 control eyes (donor ages, 20-96 years), the peripapillary sclera and penetrating vessels were investigated ultrastructurally and with antibodies against elastin, podocalyxin, and α-actin. Within the PreLR, the number and density of capillaries and the thickness of their connective tissue sheaths (CTSs) were quantified. The composition of the CTS was analyzed by using antibodies against collagen types I, III, IV, and VI, and elastin. Areas within the PreLR containing capillaries with thick or thin CTSs were determined., Results: There were no glaucomatous changes in the peripapillary elastic fibers and in the arterial capillaries in the periphery of the PreLR. In the center of the PreLR, the capillaries gained a CTS that was significantly thicker in POAG eyes than in control eyes, and the area containing capillaries with thick CTSs was significantly larger. These data did not correlate with axon counts., Conclusions: Lack of glaucomatous changes in elastic fibers of the scleral suspension of the ONH seems to prevent occlusion of penetrating vessels. In the PreLR, thickening of the capillary CTS and enlargement of the area containing capillaries with thickened CTS could increase diffusion time and may impair nutrition of the neuronal tissue.

Observations on the microvasculature in the left ventricular wall of infant and adult yaks under light and scanning electron microscope (SEM) were presented. Moreover, the diameter of different microvasculature and the density of the capillaries in three layers of the ventricular myocardium were measured using Image Pro-Plus 5.0. The results showed that the average luminal diameter of arterioles and precapillary arterioles in adult yak's hearts were, in most cases, larger than those in infant yaks. On the contrary, the diameters of the capillary in infant yak's hearts were larger than those in adult yaks. The density of capillary in the myocardium of adult yak's heart had significantly higher values (P<0.01) than those in infant yaks. Arterioles of yak's hearts were characterized by the bark-like structure and the impressions of endothelial cell nuclei, and it always gave rise to capillary after three to four grades of embranchment. The outer surface of capillaries cast in infant yak's hearts was smooth, and no constrictions were found. This was different from adult yak that always had some constrictions. The capillary anastomosis of "H" and "Y" usually existed in the myocardium of both adult and infant yaks; however, those in infant yaks were not typical as in adult yaks in their shape. The peculiar arrangement of the venules in infant yak was a "baggy" or "bulgy" arrangement, while in the adult yak, they had a root-like pattern. Our findings suggest that the patterns of microvasculature in yak's heart could be propitious to adapt better in their environment following their increase of age., (2010. © 2010 Wiley-Liss, Inc.)

Microcirculatory dysfunction plays a pivotal role in the pathogenesis of severe sepsis and septic shock; hence, microcirculation blood flow monitoring has gained increasing attention. However, microcirculatory imaging is still investigational in human sepsis and has not yet been incorporated into routine clinical practice for several reasons, including the difficult interpretation of microcirculation imaging data, difficulty to draw a parallel between sublingual microcirculation imaging and organ microcirculation dysfunction, as well as the absence of microvessel dysfunction parameters defining sequential microcirculatory changes from the early to late stages of the disease, which could aid in the context of therapeutic approaches and of prognostic parameters. The purpose of this review was to bridge the experimental abdominal organ microvascular derangement kinetics and clinical aspects of microcirculatory findings in the early phase of severe sepsis/septic shock.

Poly(D,L-lactic-co-glycolic acid) (PLGA) is a biodegradable polymer that is widely used for drug delivery. However, the degradation of PLGA alters the local microenvironment and may influence tissue structure and/or function. Here, we studied whether PLGA degradation affects the structure of the arteriolar microcirculation through arteriogenic expansion of maximum lumenal diameters and/or the formation of new smooth muscle-coated vessels. Single microspheres comprised of 50:50 PLGA (521 +/- 52.7 microm diameter), 50:50 PLGA with bovine serum albumin (BSA) (547 +/- 62.2 microm), 85:15 PLGA (474 +/- 52.6 microm), or 85:15 PLGA with BSA (469 +/- 57.2 microm) were implanted into mouse dorsal skinfold window chambers, and longitudinal arteriolar diameter measurements were made in the presence of a vasodilator (10(-4)M adenosine) over 7 days. At the end of the 7-day period, the length density of all smooth muscle-coated microvessels was also determined. Implantation of the window chamber alone elicited a 22% increase in maximum arteriolar diameter. However, the addition of 85:15 and 50:50 PLGA microspheres, bearing either BSA or no protein, elicited a significant enhancement of this arteriogenic response, with final maximum arteriolar diameters ranging from 36 to 46% more than their original size. Interestingly, the influence of PLGA degradation on microvascular structure was limited to lumenal arteriolar expansion, as we observed no significant differences in length density of smooth muscle-coated microvessels. We conclude that the degradation of PLGA microspheres may elicit an arteriogenic response in subcutaneous tissue in the dorsal skinfold window chamber; however, it has no apparent effect on the total length of smooth muscle-coated microvasculature., ((c) 2008 Wiley Periodicals, Inc.)

Rationale: Precapillary arterioles control blood flow to tissues and their correct function is vital. However, their small size has limited study and little is known concerning the calcium signals in their endothelial and muscle cells and how these relate to function., Objective: We aimed to investigate whether these small vessels are specialized in terms of structure and calcium signaling., Methods and Results: Using in situ confocal imaging we have studied the ultrastructure, Ca signaling and coordination of contraction in precapillary arterioles in ureter and vas deferens. We have compared the data to that from a small mesenteric artery. In the precapillary arteriole, 1 myocyte covers a approximately 10-microm length, and contraction of this single cell can decrease the diameter of this segment. In the mesenteric artery, more than 20 myocytes are required for this. In the precapillary arteriole, Ca signals arise solely from Ca release from the sarcoplasmic reticulum through inositol 1,4,5-trisphosphate-induced Ca release and not via ryanodine receptors. Agonist-induced Ca signals do not require Ca entry into the cell, do not spread or synchronize with neighboring cells, and are unaffected by endothelial stimulation, thereby allowing local control. This contrasts with the mesenteric artery, where Ca entry and ryanodine receptors are important and stimulation of the endothelium inhibits myocyte Ca signals and contraction., Conclusions: These data reveal the structural and signaling specializations underlying how blood flow is locally regulated, provide new insight into control of microcirculation, and provide a framework to explain its vulnerability to disease.

Marked renal vascular changes, suggestive of hypertension, were present in adult western gray kangaroos (Macropus fuliginosus) from a single facility over a 14-year period. A subset of these kangaroos also had vague clinical nervous system deficits, including blindness. To characterize the vascular lesions, determine prevalence, and document other changes, case histories and archival tissue sections from 21 adult kangaroos (8 male, 13 female) that died or were euthanatized between 1994 and 2008 were reviewed. Relevant lesions included increased thickness of the renal arteriolar tunica media with smooth muscle hypertrophy and/or hyperplasia, accumulation of extracellular matrix within arterioles, increased vascular tortuosity, and varying degrees of juxtaglomerular hyperplasia. Renal tissue from two more severely affected animals was further examined by transmission electron microscopy, highlighting arteriolar endothelial cell hypertrophy and disruption of the medial architecture. Hypertrophy of arteries and arterioles in other organ systems was also present (3/21), including vessels in the brain and spinal cord of one animal with clinical neurologic signs. Four kangaroos had antemortem retinal detachment, a potential sequel of hypertension in humans and domestic mammals. The cause of these vascular lesions in this mob is uncertain. Lesions were not associated with an infectious disease process, age, underlying renal disease, or thyroid abnormalities. In the absence of other causes, hypertension was a differential. Further investigation into clinical significance and predisposing factors, such as genetics and diet, is warranted.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common hereditary subcortical vascular dementia. It is caused by mutations in NOTCH3 gene, which encodes a large transmembrane receptor Notch3. The key pathological finding is the accumulation of granular osmiophilic material (GOM), which contains extracellular domains of Notch3, on degenerating vascular smooth muscle cells (VSMCs). GOM has been considered specifically diagnostic for CADASIL, but the reports on the sensitivity of detecting GOM in patients' skin biopsy have been contradictory. To solve this contradiction, we performed a retrospective investigation of 131 Finnish, Swedish and French CADASIL patients, who had been adequately examined for both NOTCH3 mutation and presence of GOM. The patients were examined according to the diagnostic practice in each country. NOTCH3 mutations were assessed by restriction enzyme analysis of specific mutations or by sequence analysis. Presence of GOM was examined by electron microscopy (EM) in skin biopsies. Biopsies of 26 mutation-negative relatives from CADASIL families served as the controls. GOM was detected in all 131 mutation positive patients. Altogether our patients had 34 different pathogenic mutations which included three novel point mutations (p.Cys67Ser, p.Cys251Tyr and p.Tyr1069Cys) and a novel duplication (p.Glu434&#95;Leu436dup). The detection of GOM by EM in skin biopsies was a highly reliable diagnostic method: in this cohort the congruence between NOTCH3 mutations and presence of GOM was 100%. However, due to the retrospective nature of this study, exact figure for sensitivity cannot be determined, but it would require a prospective study to exclude possible selection bias. The identification of a pathogenic NOTCH3 mutation is an indisputable evidence for CADASIL, but demonstration of GOM provides a cost-effective guide for estimating how far one should proceed with the extensive search for a new or an uncommon mutations among the presently known over 170 different NOTCH3 gene defects. The diagnostic skin biopsy should include the border zone between deep dermis and upper subcutis, where small arterial vessels of correct size are located. Detection of GOM requires technically adequate biopsies and distinction of true GOM from fallacious deposits. If GOM is not found in the first vessel or biopsy, other vessels or additional biopsies should be examined.

Regional synaptic activity induces local increases in perfusion that are coupled to upstream vasodilation and improved blood flow. In the cerebral circulation, it has been proposed that astrocytes mediate the link between the initiating stimulus and local vasodilation through propagated intracellular calcium waves. In the systemic circulation the mechanism by which local vasodilation triggers upstream alterations in blood flow involves electrotonic propagation of hyperpolarization via endothelial gap junctions, although less is known concerning the cerebral circulation. The present study aimed to investigate the extent of coupling in microvessels of the rodent brainstem and retina and the subtypes of intracellular calcium stores that might mediate astrocytic signaling. Within the brainstem, connexins (Cxs) 37 and 40 were restricted to the endothelium of pial vessels and larger penetrating arterioles, whereas astrocytic Cxs30 and 43 were found closely associated with pre- and postsynaptic neurons and nearby microvessels. Within the rat retina, Cxs37 and 40 were expressed in large radiating arterioles, but were not found in smaller vessels on the retinal surface or in the deeper retinal layers. These Cxs were absent from all retinal vessels in mice. Astrocytes, expressing Cxs30 and 43 in the rat, but only Cx43 in the mouse, were found closely associated with superficial, but not deeper blood vessels. Inositol-trisphosphate receptors (IP(3)R) 1 and 2 were expressed within brainstem astrocytes, whereas IP(3)R1 and 3 were expressed within retinal astrocytes. Limited intravascular coupling and the proximity of astrocytic networks to blood vessels supports a role for glia in activity-dependent alterations in central blood flow.

Protease-activated receptors (PARs) expressed in the endothelia and smooth muscles of vessels may play important roles in blood vessel function. Using intracellular calcium ion concentration ([Ca2+]i) imaging, we recently observed that small - but not large - arterioles of the brain responded to proteases, while testicular arterioles showed no response. The purpose of the present study was to examine the heterogeneity of the localization of PARs in arterioles using immunohistochemistry. Consistent with the [Ca2+]i imaging results, neither the thrombin receptor nor PAR2 were evident in large arterioles of the brain. However, the small arterioles of the brain, vascular smooth muscles, and endothelia showed a distinct immunoreactivity against the thrombin receptor and PAR2. The immunoreactivity of PARs in testicular arterioles was faint. In conclusion, size-dependent and/or organ-specific responses of arterioles to proteases are due to the heterogeneous localization of PARs.

Objective: To prepare a mouse model of asthma by sensitizing and challenging with house dust mite allergen Derp and evaluate its reliability by measuring airway allergy inflammation and airway responsiveness., Methods: Twelve C57BL/6J mice were randomly divided into two groups: control and asthma model. Mice of the asthma model group were sensitized by intraperitoneal injection of house dust mite allergen Derp on the first and tenth days of the experiment. From the 17th day, the mice were challenged by intranasal Derp, once every other day, seven times. The control group was treated with normal sodium instead of Derp. Twenty-four hours after the last challenge, airway responsiveness was evaluated. Bronchoalveolar lavage and histological examination of the lung were performed., Results: Airway resistance increased and dynamic lung compliance decreased significantly in the asthma model group as compared to the control group (P<0.01). When airway resistance increased by 25% and dynamic lung compliance decreased by 15%, the required metacholine concentration in the asthma model group was significantly lower than that in the control group (P<0.01). In the bronchoalveolar lavage fluid of the asthma model group, the number of total cells, absolute number of eosinophils (EOS) and the percentage of EOS in the total cell were significantly higher than those in the control group (P<0.01). Pulmonary pathological scores in the asthma model group were significantly higher than those in the control group (P<0.01). The asthma model group showed ultrastructural changes of bronchial and pulmonary arterioles. Goblet cells, mastocyte granules, and increased mucus were observed in the lung tissues of the asthma model group., Conclusions: A mouse model of asthma was prepared by sensitizing and challenging with house dust mite allergen Derp, with the characteristics of airway allergy inflammation and airway hypersensitivity reaction.

The microvascular architecture of developing lateral ventricle choroid plexus was investigated by corrosion casting and scanning electron microscopy in human fetuses aged 20 gestational weeks. The areas with different microvascular patterns corresponded to the particular parts of the mature plexus: anterior part, glomus, posterior part, the villous fringe and the free margin. In the posterior part, densely packed parallel arterioles and venules were surrounded by sheath-like capillary networks. Other areas contained compact capillary plexuses of the primary villi: the most prominent, protruding basket- and leaf-shaped plexuses were observed in the villous fringe, whilst less numerous and smaller plexuses occurred in the anterior part and glomus. The capillaries of the plexuses had a large diameter and sinusoidal dilations, and showed the presence of occasional short, blind sprouts indicative of angiogenesis. Short anastomoses between arterioles supplying the plexuses and venules draining them were only rarely observed. In the upper area of the choroid plexus, the superior choroidal vein was surrounded by a capillary network forming small, glomerular or rosette-shapes plexuses. The free margin of the choroid plexus was characterized by flat, multiple, arcade-like capillary loops. The general vascular architecture of the human choroid plexus at 20 gestational weeks seems to be similar to that of postnatal/mature plexus, still lacking, however, the complex vascular plexuses of the secondary villi.

An instrument is demonstrated that is capable of three-dimensional (3D) vasculature imaging and pO(2) quantification with high spatial resolution. The instrument combines two-photon (2P) microscopy with phosphorescence quenching to measure pO(2). The instrument was demonstrated by performing depth-resolved microvascular pO(2) measurements of rat cortical vessels down to 120 microm below the surface. 2P excitation of porphyrin was confirmed, and measured pO(2) values were consistent with previously published data for normoxic and hyperoxic conditions. The ability to perform 3D pO(2) measurements using optical techniques will allow researchers to overcome existing limitations imposed by polarographic electrodes, magnetic resonance techniques, and surface-only pO(2) measurement techniques.

Mitochondrial H2O2 contributes to flow-mediated dilation (FMD) in human coronary arterioles (HCA). We examined the hypothesis that the endothelial cytoskeleton plays a critical role in transducing endothelial wall shear stress into a stimulus for releasing mitochondrial ROS. Phallacidin together with alpha-, beta-tubulin antibodies and Mito-Tracker Red showed the proximity of F-actin, microtubules and mitochondria in endothelial cells. Cytochalasin D (CytoD) and nocodazole (Noc) disrupted endothelial F-actin and microtubules in HCA, respectively, concurrent with a reduction in the generation of cytosolic and H2O2 (hydroethidine and dichlorodihydrofluorescein fluorescence) and mitochondrial superoxide (mitoSox) during flow (control: 3.5 +/- 1.6, Cyto D: 0.51 +/- 0.2, Noc: 0.81 +/- 0.6). FMD, but not the dilation to bradykinin or papaverine, was reduced by Cyto D (26 +/- 10% vs. 56 +/- 3%) or Noc (26 +/- 11% vs. 58 +/- 7%). These results suggest that cytoskeletal elements are a critical component of the signaling mechanism linking endothelial shear stress and mitochondrial release of ROS in the human coronary microcirculation.

Background and Purpose: High-dose human albumin is robustly neuroprotective in preclinical ischemia models and is currently in phase III clinical trial for acute ischemic stroke. To explore the hypothesis that albumin's protective effect is mediated in part by salutary intravascular mechanisms, we assessed microvascular hemodynamics in a model of laser-induced cortical arteriolar thrombosis., Methods: The cortical microcirculation of anesthetized, physiologically monitored Sprague-Dawley rats was studied in vivo via a frontoparietal cranial window (intact dura) by two-photon laser-scanning microscopy after plasma-labeling with fluorescein-dextran. Focal thrombosis was produced in 30- to 50-mum cortical arterioles by laser irradiation. Arteriolar flow velocity was measured repeatedly by line-scanning. At 30 minutes post-thrombosis, animals were treated with either human albumin, 2 g/kg, or with saline control., Results: Baseline arteriolar flow velocity averaged 3.5+/-1.8 mm/s and was reduced to 10% to 13% of control values by laser-induced thrombosis, which also led to focal vasodilatation (mean, 49% above baseline diameter). Saline treatment at 30 minutes post-thrombosis failed to influence arteriolar flow velocity, which remained depressed at 10% to 22% of control throughout the subsequent 60- to 90-minute observation period. By contrast, albumin treatment induced a prompt rise in median flow velocity to 38% of control by 10 minutes post-treatment, and to 61% to 67% of control by 50 to 60 minutes., Conclusions: High-dose albumin therapy induces a prompt, sustained improvement in microvascular hemodynamics distal to a cortical arteriolar thrombosis; these data support an important intravascular component to albumin's protective effect in acute cerebral ischemia.

Objective: To examine the effects of the renin-angiotensin system (RAS) on renal arterioles to determine the association between the distribution of angiotensin II AT1 receptors and the morphologic and physiologic heterogeneity of renal arterioles., Study Design: To estimate the number of angiotensin II AT1 receptors along the length of the arterioles and per arteriole, we combined immunoelectron microscopy with stereology., Results: The number of AT1 receptor molecules was significantly lower in the renin-positive smooth muscle cells (SMCs) than in the renin-negative SMCs of the afferent and efferent arterioles. There were no significant differences along and between the afferent and efferent arterioles in relative number of AT1 receptors of endothelial cells or SMCs., Conclusion: Our results suggest that the heterogeneous activity of angiotensin II in SMCs and the different permeabilities of the endothelium along the afferent arterioles are probably not controlled directly by angiotensin II AT1 receptors. However, the activity of the RAS is possibly involved in the significantly reduced number of receptors in renin-granulated cells. An understanding of how the number of AT1 receptors on the SMC surface is controlled may furnish a new path for pharmacologically changing RAS activity on SMCs.

It was previously reported that Mato cells (Mato's fluorescent granular perithelial cells) were frequently localized in the bifurcating areas of cerebral arterioles and occasionally, collagen fibers appeared close to Mato cells of aged rats. It has also been established that Mato cells were scavenger cells in the cerebral tissue and provided with MHC-class II antigen. The present paper deals with the relationship between the distribution of collagen fibers and Mato cells in the bifurcating area of cerebral arterioles. 6 Wistar rats (3 rats aged 4 months and 3 rats aged 16 months) were employed for this electron microscopical study. They were perfused with the mixture of paraform-glutaraldehyde solution, and cerebral cortices were excised and fixed with 1% osmic solution and embedded in Epon 812. In order to observe the bifurcating area of cerebral arterioles, serial semithin sections cutting with the diamond knife were stained with toluidine blue, and checked under the light microscope. After obtaining available regions, serial thin sections were stained with uranyl acetate and lead nitrate, and observed with Hitach H7600 electron microscope. In order to survey the distribution of collagen fibers, 2 groups of the specimens of 4 months old (2 rats) and 5 groups of specimens of 16 months old rats (2 rats) were prepared. Each group consisted of serial 10 thin sections. Other rats of young and aged were used for complementary use. From the observation, it is confirmed that in the cerebral arteriole, collagen fibers are localized only in the interstices around Mato cells, and the fibers appear in a small quantity in the rats aged 4 months, while a certain amounts of the fibers are arranged sporadically in the rats aged 16 months. However, no collagen fibers can be detected in the subendothelial space and in the interstices among smooth muscle cells of cerebral arteriole. If Mato cells lack in some regions of cerebral arterioles, collagen fibers cannot be recognized. The following is also to be stressed that no fibroblastoid cells do appear in any serial sections of cerebral arterioles. From these findings, it seems possible that Mato cells play a principal role in the formation of collagen fibers in the cerebral arterioles, and associate with the sclerosis of cerebral arterioles.

It was previously reported that Mato cells (Mato's fluorescent granular perithelial cells) were frequently localized in the bifurcating areas of cerebral arterioles and occasionally, collagen fibers appeared close to Mato cells of aged rats. It has also been established that Mato cells were scavenger cells in the cerebral tissue and provided with MHC-class II antigen. The present paper deals with the relationship between the distribution of collagen fibers and Mato cells in the bifurcating area of cerebral arterioles. 6 Wistar rats (3 rats aged 4 months and 3 rats aged 16 months) were employed for this electron microscopical study. They were perfused with the mixture of paraform-glutaraldehyde solution, and cerebral cortices were excised and fixed with 1% osmic solution and embedded in Epon 812. In order to observe the bifurcating area of cerebral arterioles, serial semithin sections cutting with the diamond knife were stained with toluidine blue, and checked under the light microscope. After obtaining available regions, serial thin sections were stained with uranyl acetate and lead nitrate, and observed with Hitach H7600 electron microscope. In order to survey the distribution of collagen fibers, 2 groups of the specimens of 4 months old (2 rats) and 5 groups of specimens of 16 months old rats (2 rats) were prepared. Each group consisted of serial 10 thin sections. Other rats of young and aged were used for complementary use. From the observation, it is confirmed that in the cerebral arteriole, collagen fibers are localized only in the interstices around Mato cells, and the fibers appear in a small quantity in the rats aged 4 months, while a certain amounts of the fibers are arranged sporadically in the rats aged 16 months. However, no collagen fibers can be detected in the subendothelial space and in the interstices among smooth muscle cells of cerebral arteriole. If Mato cells lack in some regions of cerebral arterioles, collagen fibers cannot be recognized. The following is also to be stressed that no fibroblastoid cells do appear in any serial sections of cerebral arterioles. From these findings, it seems possible that Mato cells play a principal role in the formation of collagen fibers in the cerebral arterioles, and associate with the sclerosis of cerebral arterioles.

The hepatic artery plays an important role in the nourishment of liver parenchyma. The arterial distribution generates debate on where the artery terminates in the liver although is accepted that terminal branching of hepatic artery opened into sinusoids and form arterio-portal anastomosis. This implies that sinusoids are fed by both arterial and portal vessels characterized by different pressures. The presence of a double feeding to the sinusoids from the vena porta, at a pressure of 6-7 cm H2O, and from the hepatic artery, at a pressure of 12-25 cm H2O, has generated many studies for the need to explain the prevalence of flow from the vena porta. For this reason, we have studied the terminal hepatic artery branches in the rat by using special microvascular corrosion casting procedure which makes possible to better follow the hepatic artery terminal branches. Twelve young sexually mature male and female Wistar rats were used in this study. More than one hundred vascular corrosion casts of terminal hepatic arterioles were studied by Scanning Electron Microscopy. Histological samples were prepared using standard techniques for light microscopy. The experimental approach allow to easily follow the three-dimensional course of hepatic artery branches which is extremely difficult in standard injections. In all our observations of the rat liver vascular corrosion casts, terminal hepatic artery branches do not end directly in the sinusoidal beds. Terminal hepatic artery branches end into peribiliary plexus, periportal plexus and single capillaries of the portal space. We have not found any arterio-venous shunt nor any arterial vessel flowing into a venous vessel or a sinusoid. This means that only venous blood at a lowered pressure reaches the vena porta branches and the sinusoids.

Objective: Given evidence for clustering of signalling molecules and ion channels in cholesterol-rich membrane domains, the involvement of such structures in arteriolar smooth muscle mechanotransduction was examined., Method: To determine the contribution of smooth muscle cholesterol-rich membrane domains to the myogenic response, isolated arterioles were exposed to the cholesterol-depleting agent beta-cyclodextrin (1-10 mM) in the absence and presence of excess exogenous cholesterol., Results: beta-Cyclodextrin significantly impaired pressure-induced vasoconstriction, while excess cholesterol attenuated this effect. Impaired myogenic constriction was evident in de-endothelialized vessels, indicating an action at the level of smooth muscle. beta-Cyclodextrin treatment uncoupled increases in intracellular Ca(2+) from myogenic constriction and depleted intracellular Ca(2+) stores consistent with a loss of connectivity between plasma membrane and sarcoplasmic reticulum signalling. However, beta-cyclodextrin-treated arterioles showed unaltered constrictor responses to KCl and phenylephrine. Electron microscopy verified that beta-cyclodextrin caused a decrease in caveolae, while confirmation of smooth muscle containing caveolae was obtained by immunostaining for caveolin-1. Viability of beta-cyclodextrin-treated arterioles was confirmed by agonist sensitivity and propidium iodide nuclear staining., Conclusion: The data suggest that smooth muscle cholesterol-rich membrane domains contribute to the myogenic response. Further studies are required to determine whether this relates to specific mechanosensory events or generalized alterations in membrane function.