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PURPOSE: To investigate the effects of human chorionic gonadotropin (hCG) on the testicular tissue of young male rats.METHODS: Male Wistar rats were assigned to groups (10 rats/group).Control Group received subcutaneous saline solution; Group 1 received hCG 50UI/Kg/dose; and Group 2 received hCG 100UI/Kg/dose, daily for 15 days. Half was submitted to bilateral orchiectomy on the 16th day and the other half 45 days after the beginning of the hormone application. Testicles were weighed, measured and has their volumes determined. The diameter of the tubules and the thickness of the seminiferous epithelium were measured.RESULTS: Control Group presented the highest values of testicles volume and weight. Rats in the Control presented normal histology. In G1 and G2 atrophy of the seminiferous tubules, apoptosis of germ cells and multinucleated giant cells were observed. Comparing groups, in the first operation Control rats had higher diameter values. In the second operation, the Control was only different from G1. As for thickness, Control had higher values in both operations. Comparing the time of operation, the diameter values were higher in G1 and G2 in the second operation. For all groups, the thickness of the epithelium was higher in the second operation.CONCLUSIONS: Human chorionic gonadotropin is gonadotoxic in rats. This effect was temporary and can affect reproductive potential. The total recovery of testicular damage in the studied range could not be proved, and the effects were not dose-dependent.

Background: One of the challenges in positron emission tomography (PET) is labelling complex aliphatic molecules., Objective: This study aimed to develop a method of metal-catalysed radiofluorination that is site-selective and works in moderate to good yields under facile conditions., Methods: Herein, we report on the optimisation of an aliphatic C-H to C- 18 F bond transformation catalysed by a Mn(porphyrin) complex., Results: The successful oxidation of 11 aliphatic molecules, including progesterone, is reported. Radiochemical Incorporations (RCIs) up to 69% were achieved within 60 min without the need for pre-activation or special equipment., Conclusion: The method features mild conditions (60 °C) and promises to constitute a valuable approach to labelling of biomolecules and drug substances., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

A new family of robust, non-toxic, water-compatible ruthenium(II) vinyl probes allows the rapid, selective and sensitive detection of endogenous carbon monoxide (CO) in live mammalian cells under normoxic and hypoxic conditions. Uniquely, these probes incorporate a viscosity-sensitive BODIPY fluorophore that allows the measurement of microscopic viscosity in live cells via fluorescence lifetime imaging microscopy (FLIM) while also monitoring CO levels. This is the first example of a probe that can simultaneously detect CO alongside small viscosity changes in organelles of live cells., (© 2020 The Authors. Published by Wiley-VCH GmbH.)

A series of new ruthenium(II) vinyl complexes has been prepared incorporating perylenemonoimide (PMI) units. This fluorogenic moiety was functionalised with terminal alkyne or pyridyl groups, allowing attachment to the metal either as a vinyl ligand or through the pyridyl nitrogen. The inherent low solubility of the perylene compounds was improved through the design of poly-PEGylated (PEG=polyethylene glycol) units bearing a terminal alkyne or a pyridyl group. By absorbing the compounds on silica, vapours and gases could be detected in the solid state. The reaction of the complexes [Ru(CH=CH-Per Im )Cl(CO)(py-3PEG)(PPh 3 ) 2 ] and [Ru(CH=CH-3PEG)Cl(CO)(py-Per Im )(PPh 3 ) 2 ] with carbon monoxide, isonitrile or cyanide was found to result in modulation of the fluorescence behaviour. The complexes were observed to display solvatochromic effects and the interaction of the complexes with a wide range of other species was also studied. The study suggests that such complexes have potential for the detection of gases or vapours that are toxic to humans., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Optical sensing offers a low-cost and effective means to sense carbon monoxide in air and in solution. This contribution reports the synthesis of a new series of vinyl complexes [Ru(CH=CHR)Cl(CO)(TBTD)(PPh 3 ) 2 ] (R=aryl, TBTD=5-(3-thienyl)-2,1,3-benzothiadiazole) and shows them to be highly sensitive and selective probes for carbon monoxide in both solution and air. Depending on the vinyl substituent, chromogenic and fluorogenic responses signalled the presence of this invisible, odourless, tasteless and toxic gas. Adsorbing the complexes on silica produced colorimetric probes for the 'naked eye' detection of CO in the gas phase with a limit of detection as low as 8 ppm in some cases, while the release of the TBTD fluorophore allowed detection at much lower concentrations through the fluorescence response. Structural data were obtained by single-crystal X-ray diffraction techniques, while the photophysical behaviour was explored computationally using TD-DFT experiments. The systems were also shown to be selective for CO over all other gases tested, including water vapour and common organic solvents. By introducing a poly(ethylene)glycol chain to the vinyl functionality, water compatibility was achieved and these non-cytotoxic complexes were employed in the sensing of CO in HeLa cells, offering a simple and rapid system for sensing this gasotransmitter in this challenging medium., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A two-photon fluorescent probe based on a ruthenium(II) vinyl complex is capable of selectively detecting carbon monoxide in cells and ex vivo using mice with a subcutaneous air pouch as a model for inflammation. This probe combines highly selective and sensitive ex vivo detection of endogenous CO in a realistic model with facile, inexpensive synthesis, and displays many advantages over the widely used palladium-based systems.

The versatile rhenium complex [ReCl(CO) 3 (bpyC[triple bond, length as m-dash]CH)] (HC[triple bond, length as m-dash]Cbpy = 5-ethynyl-2,2'-bipyridine) is used to generate a series of bimetallic complexes through the hydrometallation of [MHCl(CO)(BTD)(PPh 3 ) 2 ] (M = Ru, Os; BTD = 2,1,3-benzothiadiazole). The ruthenium complex [Ru{CH[double bond, length as m-dash]CH-bpyReCl(CO) 3 }Cl(BTD)(CO)(PPh 3 ) 2 ] was characterised structurally. Ligand exchange reactions with bifunctional linkers bearing oxygen and sulfur donors provide access to tetra- and pentametallic complexes such as [{M{CH[double bond, length as m-dash]CH-bpyReCl(CO) 3 }(CO)(PPh 3 ) 2 } 2 (S 2 CNC 4 H 8 NCS 2 )] and Fe[C 5 H 4 CO 2 M{CH[double bond, length as m-dash]CH-bpyReCl(CO) 3 }(CO)(PPh 3 ) 2 ] 2 . The effect of the group 8 metal on the photophysical properties of the rhenium centre was investigated using the complexes [Ru{CH[double bond, length as m-dash]CH-bpyReCl(CO) 3 }Cl(BTD)(CO)(PPh 3 ) 2 ] and [M{CH[double bond, length as m-dash]CH-bpyReCl(CO) 3 }{S 2 P(OEt) 2 }(CO)(PPh 3 ) 2 ] (M = Ru, Os). This revealed the quenching of the rhenium-based emission in favour of weak radiative processes based on the Ru and Os centres. The potential for exploiting this effect is illustrated by the reaction of [Ru{CH[double bond, length as m-dash]CH-bpyReCl(CO) 3 }Cl(CO)(BTD)(PPh 3 ) 2 ] with carbon monoxide, which results in a 5-fold fluorescence enhancement in the dicarbonyl product, [Ru{CH[double bond, length as m-dash]CH-bpyReCl(CO) 3 }Cl(CO) 2 (PPh 3 ) 2 ], as the quenching effect is disrupted.

The disulfide ligand (SC 6 H 4 CO 2 H-4) 2 acts as a simple but versatile linker for a range of group 8 transition metals through reaction of the oxygen donors. This leads to a range of homobimetallic ruthenium and osmium alkenyl compounds, [{M(CH═CHR)(CO)(PPh 3 ) 2 (O 2 CC 6 H 4 S-4)} 2 ] (M = Ru, Os; R = C 6 H 4 Me-4). Additional metal-based functionality can be added through the use of precursors incorporating rhenium bipyridine units (R = (bpy)ReCl(CO) 3 ). The more robust diphosphine ligands in [{Ru(dppm) 2 (O 2 CC 6 H 4 S-4)} 2 ] 2+ (dppm = diphenylphosphinomethane) allow reduction of the disulfide bond with sodium borohydride to yield the thiol complex [Ru(O 2 CC 6 H 4 SH-4)(dppm) 2 ] + . This complex reacts with [AuCl(PPh 3 )] to afford the bimetallic compound [Ru(dppm) 2 (O 2 CC 6 H 4 S-4)Au(PPh 3 )] + . However, an improved route to the same and related heterobimetallic compounds is provided by the reaction of cis-[RuCl 2 (dppm) 2 ] with [Au(SC 6 H 4 CO 2 H-4)(L)] (L = PPh 3 , PCy 3 , PMe 3 , IDip) in the presence of base and NH 4 PF 6 (IDip = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene). The heterotrimetallic compound [Au(SC 6 H 4 CO 2 Ru(dppm) 2 ) 2 ] + is accessible through the reaction of the homoleptic gold(I) dithiolate [Au(SC 6 H 4 CO 2 H-4) 2 ]PPN (PPN = bis(triphenylphosphine)iminium) with cis-[RuCl 2 (dppm) 2 ]. Without departure from the same methodology, greater complexity can be incorporated into the system to provide the penta- and heptametallic assemblies [(dppf){AuSC 6 H 4 CO 2 Ru(dppm) 2 } 2 ] 2+ and [(dppf){AuSC 6 H 4 CO 2 Os(CH═CH-bpyReCl(CO) 3 )(CO)(PPh 3 ) 2 } 2 ]. The same stepwise approach provides the dinuclear organometallic complexes [(L)Au(SC 6 H 4 CO 2 -4)M(CH═CHC 6 H 4 Me-4)(CO)(PPh 3 ) 2 ] (M = Ru, Os; L = PPh 3 , IDip). Complexes containing three metals from different groups of the periodic table [(L)Au(SC 6 H 4 CO 2 -4)M{CH═CH-bpyReCl(CO) 3 }(CO)(PPh 3 ) 2 ] (M = Ru, Os) can also be prepared, with one ruthenium example (L = PPh 3 ) being structurally characterized. In order to illustrate the versatility of this approach, the synthesis and characterization (IR and NMR spectroscopy, TEM, EDS, and TGA) of the functionalized gold and palladium nanoparticles Au@[SC 6 H 4 CO 2 Ru(dppm) 2 ] + and Pd@[SC 6 H 4 CO 2 Ru(dppm) 2 ] + is reported.

Advances in neuroscience, engineering and computer technologies are creating opportunities to connect the brain directly to devices to treat a variety of disorders, both neurological and psychiatric. They are opening a new field of neuroscience called "neurotechnology." This article reviews efforts in this area that are ongoing at Brown University and the hospitals affiliated with Brown's Alpert Medical School. Two general approaches are being used. One uses advanced electrodes to "sense" the activity of many individual neurons in the cerebral cortex and then use that activity for therapeutic purposes. The other uses various types of devices to stimulate specific networks in the brain in order to restore normal function and alleviate symptoms.

The up-regulation of the keratan sulfate proteoglycan (ABAKAN) was examined using indirect immunohistochemical methods. Previous studies indicate that the keratan sulfate proteoglycan is associated with astrocytes in the optic nerve and in the developing rat brain. In model culture systems, this proteoglycan is capable of inhibiting the growth of neurites over laminin. To determine whether the proteoglycan is up-regulated specifically during reactive gliosis, stab wounds were made in the cerebral cortex of early postnatal rats, and the up-regulation of the proteoglycan was related to the developmentally regulated gliotic response to injury. Following a stab wound in the cortex of the late postnatal rat, reactive gliosis was consistently observed along with an up-regulation of ABAKAN. When the cortex was injured on postnatal day 2, there was a variable gliotic response and considerable variation in the regulation of proteoglycan expression. Biochemical analysis revealed that ABAKAN is a large proteoglycan with multiple keratan sulfate side-chains, at least one chondroitin sulfate side-chain and at least one additional carbohydrate chain with a terminal 3-sulfoglucuronic acid. Taken together, these data demonstrate that the boundary proteoglycan ABAKAN is also associated with reactive gliosis during early postnatal development.

Cultured Schwann cells were implanted into the thoracic spinal cords o f adult rats inside thin tubes made of polycarbonate film coated with poly-L-lysine. Additional control tubes were implanted which did not contain cultured Schwann cells. Some of the control tubes were coated with poly-L-lysine and others were not. One week to 2 months later the animals were perfused with fixatives and the tubes were prepared for light or electron microscopy. Immunocytochemical studies of the Schwann cell tubes reveal that they contain axons. Most of these axons are grouped in fascicles that run longitudinally through the tubes. The distribution of these axons matches precisely the distribution of basal lamina within the tubes as displayed by immunolabeling with an antibody to laminin. Surprisingly, the same patterns of labeling are seen in the control tubes, although they contain fewer axons. Control tubes lacking poly-L-lysine contain the fewest. Electron microscopy verifies that the tubes, including control tubes, contain Schwann cells and axons of different diameters. Furthermore, the Schwann cells ensheathe and myelinate the axons. These results strengthen the hypothesis that Schwann cells can support axonal growth in the spinal cords of adult animals. They also demonstrate that these Schwann cells can be implanted or they can be derived from the host animal. This finding raises the possibility that therapies could be devised for bridging spinal cord lesions that are based on maximizing migration of endogenous host cells into the sites of lesions.

Migration and differentiation of immature neurons in the retina and optic tectum were studied using retrograde transport of DiI and immunocytochemistry. The results demonstrate that many of these cells migrate via a method of perikaryal translocation. DiI was applied to the optic nerves or tecta in fixed chick embryos (Embryonic Days 4-10); 1-2 months later the tissues were dissected and examined as whole mounts or vibratome sections using fluorescent and confocal microscopy. In both the retina and the optic tectum many labeled cells have a bipolar shape with leading and trailing processes contacting the pial and ventricular surfaces, respectively. Axons grow from the leading processes before somata reach their final locations and dendrites sometimes begin to grow prior to retraction of trailing processes. Immunocytochemical studies using a monoclonal antibody (TUJ1) specific for postmitotic neurons show a similar pattern. These results indicate that neuronal migration occurs via more than one mode. In thin tissues like the retina and newly forming optic tectum, many postmitotic neurons migrate by translocating their somata while retaining connections with the pial and/or ventricular surfaces. In thicker, more complex tissues like the maturing optic tectum, cerebral cortex, and cerebellum, most young neurons appear to detach from the surfaces and migrate along processes of radial glia or other cell types.

ABAKAN is a keratin sulfate proteoglycan that was identified in rat brain by monoclonal antibody TED15 (Geisert et al. [1992] Brain Res. 571:165-168). It blocks neuronal attachment and neurite outgrowth in culture, is associated with astrocytes, and marks the boundaries of areas in the developing rat brain (Geisert and Bidanset [1993] Dev. Brain Res., 75:163-173). In the present study TED15 was used to examine the distribution of ABAKAN during laminar development of the dorsal lateral geniculate nucleus in ferrets. This distribution was also compared with that of astrocytes as displayed with antibodies to GFAP. In the adult, TED15 and anti-glial fibrillary acidic protein (GFAP) labeling are similar. Both are fairly uniform in the nucleus although somewhat elevated near the optic tract and in the interlaminar zone between laminae A and A1. During development the pattern is quite different. At postnatal day 1 (P1), before lamination is evident, TED15 and anti-GFAP labeling are light in the nucleus. By P10, when laminae are emerging, both are elevated in the A-A1 interlaminar zone and in the C laminae. At P18, when laminae are distinct, TED15 labels the A-A1 interlaminar zone, and it marks the borders between the ON and OFF leaflets within A and A1 (Stryker and Zahs [1983] J. Neurosci. 3:1943-1951). In comparison, anti-GFAP marks the interlaminar zone but not the ON/OFF leaflets. By 6 weeks the nucleus resembles the adult nucleus. These results show that ABAKAN marks the boundaries of the major functional subdivisions of the lateral geniculate nucleus in the developing ferret and suggest that it plays a role in lamination.

Neurogenesis, migration and maturation of ganglion cells in the posterior pole of chick retina have been studied using embryonic incorporation of [3H]thymidine, immunocytochemistry and retrograde labeling. Unlike previous studies, we have examined the neurogenesis of independently identified ganglion cells that have survived the period of naturally occurring cell death (embryonic days 11-16). Embryos were labeled with [3H]thymidine at different embryonic ages (embryonic days 3, 5 and 7). After the chicks hatched, ganglion cells were retrogradely labeled with rhodamine microspheres and the retinas were processed for autoradiography and fluorescent microscopy. The results indicate that 40% of the ganglion cells in the posterior pole undergo a final mitosis by embryonic day 3 and that more than 25% of the ganglion cells are born on or after embryonic day 7. These results also suggest that naturally occurring cell death does not preferentially affect ganglion cells born on specific embryonic days. Using immunocytochemistry with an antibody against neuron-specific beta-tubulin and retrograde labeling with the carbocyanine dye DiI we show that ganglion cells begin to differentiate before the completion of their migration to the presumptive ganglion cell layer. These results suggest the following developmental sequence. (1) Ganglion cells of the posterior pole undergo their final mitosis near the ventricular margin between embryonic days 2 and 8. (2) They maintain contacts with both retinal surfaces and their nuclei move toward the ganglion cell layer. At this time they start to differentiate, expressing a form of neuron-specific tubulin and growing axons that can reach the optic chiasm. (3) Once migration is completed dendritic development commences.

In the visual system of the cat the projection from the retina to the lateral geniculate nucleus has been studied extensively. However, the patterns of synaptic contacts made by individual axons onto individual cells have not been described. In this study these patterns have been examined for class 1 cells (Guillery: J Comp Neurol 128:21, '66). Retinogeniculate axons and lateral geniculate neurons are labeled with horseradish peroxidase (HRP) via injections into the optic tracts and optic radiations, respectively. Sections are then processed for combined light and electron microscopic analysis. They are examined with the light microscope to identify labeled lateral geniculate neurons that appear to be contacted by labeled retinal axons. These cells and axons are then analyzed by a computerized microscope system, and sites of apparent synaptic contact are recorded. This light microscopic analysis indicates that individual class 1 cells are contacted by many retinogeniculate axons (> 10) and that each of these axons contacts many lateral geniculate neurons (> 20). Some axons make numerous contacts that are concentrated onto a few dendrites, while others make only a few contacts, which are spread over several dendrites. In all cases, the majority of contacts are on the dendritic shafts of relatively thick secondary and tertiary dendrites. Electron microscopic analysis confirms that most of the contacts identified with the light microscope are synaptic. It also reveals that labeled and unlabeled retinal axons can innervate the same dendritic segment. Finally, one cell was studied that had its soma and most of its dendrites in lamina A1 but some of its dendrites extended into lamina A. This cell received input from retinal axons in both layers, thus suggesting that it may have been binocularly excitable.

Growing axons require an appropriate substrate on which to elongate. In the peripheral nervous system Schwann cells provide this substrate, and in the developing central nervous system (CNS) astrocytes are involved. In the adult CNS damaged axons do not normally regenerate but they can grow through peripheral nerve grafts. Also, they can grow along sheets of implanted Schwann cells or astrocytes. This study examines the ability of dissociated suspensions of Schwann cells and astrocytes to support axonal growth when implanted into the brains of adult rats. Schwann cells and astrocytes are cultured from near-term rat fetuses or newborn pups. They are transferred to polycarbonate tubes, and one end of each tube is inserted into the dorsal thalamus. The other end is secured extracranially. After 4 weeks to 6 months, the tubes are filled with tissue and are well vascularized. Evidence that Schwann cells support axonal growth comes from retrograde labeling studies in which horseradish peroxidase is applied to the extracranial ends of the tubes. In addition, immunolabeling reveals axon-like fibers inside the tubes using three neuron-specific antibodies. Finally, electron microscopy shows that these tubes contain small peripheral nerve-like structures consisting of myelinated and unmyelinated axons and a perineurial wrapping. Tubes filled with astrocytes contain less tissue than Schwann cell tubes and cells in the brain could not be retrogradely labeled by applying HRP to the extracranial ends. However, immunocytochemical studies reveal axon-like fibers extending for several millimeters into these tubes although few, if any, reach the external end.

This paper describes a new transplantation method for testing the ability of purified populations of glial cells to support axonal growth in the brains of adult animals. Thin tubes, rolled from porous polycarbonate film, are coated with poly-L-lysine and filled with cultured Schwann cells. Schwann cell-filled tubes or control tubes (poly-L-lysine coated only) are then implanted into the brains of adult rats so that one end of the tube is in the thalamus and the other extends extracranially. After survival times of 4-16 weeks horseradish peroxidase (HRP) is applied to the extracranial end of the tube. One or two days later the animal is perfused and the brain is sectioned and processed histochemically. Results show that tubes containing Schwann cells are densely filled with tissue and are well vascularized. Further, neurons in the central nervous system are retrogradely labeled with HRP and most labeled cells are concentrated in regions of the diencephalon near the end of the tube. Control tubes contain very little tissue and show no evidence that they support axonal growth. These results are consistent with the hypothesis that Schwann cells can support axonal growth in the brains of adult rats.

This report examines the morphological changes that occur in a line of human neuroblastoma cells (LA-N-5) following treatment with retinoic acid, in vitro. The results demonstrate that retinoic acid induces pronounced differentiation of these cells. Perikarya aggregate into tight clusters and extend long processes that are frequently fasciculated. Growth cones appear at the ends of these processes. Transmission electron microscopy reveals that after 10 days of treatment these long neurites give rise to varicosities which contain clusters of large dense-core vesicles and smaller clear vesicles. After 18 days of treatment the cultures cease to differentiate further. The pattern of neurite outgrowth is very complex by this point and the frequency of growth cones and vesicle-containing varicosities is greatly increased compared with shorter treatments. Most of these varicosities contain a mix of large dense-core vesicles and smaller clear vesicles and in some profiles the clear vesicles are round while in others they are pleomorphic. Despite this increase in the number of vesicle-containing profiles no membrane specializations were seen that resemble mature synapses. The present results demonstrate that retinoic acid can produce morphological changes in these cells in culture, and that these changes closely mimic those of normal differentiating neurons in culture. Considered with previous studies, these findings suggest that this cell line might provide a useful model system for studying neural differentiation.

A rapid method for the detection of Escherichia coli in blood has been developed. The method employs blood cell lysis, staining of bacteria with ethidium bromide, and detection of stained bacteria using flow cytometry. The detection protocol requires less than 2 h sample handling time and is not dependent on bacterial growth. This method has been applied to human donor blood specimens seeded with various E. coli concentrations and to two rabbit model systems. Bacterial detection is evident from the in vitro human blood studies at levels of 10 E. coli/ml and from in vivo rabbit model studies at less than 100 E. coli/ml.

The effects of congenital monocular microphthalmia on the development of the lateral geniculate nucleus were examined in a 10-week-old cat. The left eye and optic nerve in this animal appear normal. The right eye is about 30% smaller in volume than the left and the optic nerve from this eye has a cross-sectional area that is only 15% that of the left. In addition, this nerve contains few, if any, large myelinated axons. Both lateral geniculate nuclei are abnormal and the abnormality differs rostrally and caudally. The caudal portion most closely resembles the normal nucleus. Retinal input from both eyes is segregated into cellular laminae that are separated from each other by cell sparse interlaminar zones. However, the input from the microphthalmic eye seems to be sparse and patchy and it does not support normal cell growth. All neurons, including glutamic acid decarboxylase-positive (GAD+) neurons, in laminae innervated by the small eye are reduced in size in a pattern similar to that seen following the removal of retinal input. In comparison, the rostral portion of the nucleus receives very little input from the microphthalmic eye. Instead the normal eye densely innervates nearly the entire nucleus. In this region, interlaminar zones fail to form but the input from the normal eye is able to support cell growth including the growth of GAD+ neurons.

Retino-geniculate axons in the cat were induced to grow abnormally by cutting one optic nerve in kittens. Surviving optic tract axons that had grown into the denervated regions were then filled in the adults with horseradish peroxidase to reveal the terminal arbors of individual axons. Two types of abnormal axonal growth are described--translaminar growth and monocular segment growth. Translaminar growth is the most common and occurs between laminae in the binocular part to the nucleus. Axons giving rise to translaminar growth do not branch as they pass through the denervated regions of the nucleus. Instead, the abnormal branches originate from portions of the terminal arbor within the normal target lamina. These axons look like normal retino-geniculate axons in terms of their branching patterns, cytological features, and patterns of synaptic contacts except that parts of their terminal arbors have expanded to innervate inappropriate laminae. The distribution of translaminar branches overlaps the distribution of a restricted group of surviving large neurons that have not undergone denervation atrophy. Monocular segment growth invades the lateral pole of the nucleus directly from the optic tract. These branches arise from axons passing through or near the denervated region and appear to represent the formation of new terminal arbors. The synaptic swellings arising from these branches have cytological features like the synaptic swellings arising from translaminar branches and they form similar patterns of synaptic contacts. However, monocular segment branches degenerate more rapidly when damaged and they are not associated with surviving large neurons.

The glycoprotein laminin is a prominent constituent of basal laminae and has been suggested to play an important role in axonal growth. We have tested this hypothesis, by examining the temporal and spatial distribution of laminin in the rat spinal cord, relative to elongating corticospinal tract (CST) axons, during normal development and after newborn and adult spinal lesions. The distribution of laminin was demonstrated in spinal cord sections from animals ranging in age from 14 days embryonic to adult using immunocytochemistry. Anti-laminin immunolabeling was seen around blood vessels and meninges in all the animals examined. However, within the grey and white matter its distribution was age-dependent. In the normal cord, immunostaining appeared in small amounts in early embryos, but was absent from all postnatal animals even at ages when the CST was growing down the cord. Following injury, intense immunostaining was associated with lesions in both newborn and adult operates at all postoperative periods examined. Within the matrix of the lesion laminin immunostaining was especially prominent. In the intact cord it was prominent only around blood vessels near the lesion site. Our results indicate that the distribution of laminin does not closely correlate with axonal growth of the CST either during normal development or after spinal injury.

Displaced ganglion cells were studied in the rabbit retina after filling them with horseradish peroxidase via injections into the optic nerve. These cells are primarily in areas outside of the visual streak. They are larger than other inner nuclear layer cells and are the size of the smallest neurons in the ganglion cell layer. Large labeled cells (greater than 20 microns) are found only in the ganglion cell layer. These findings further illustrate the wide variability in the size and distribution of displaced ganglion cells in the retinas of different mammals.

Ther terminal arbors of individual retinogeniculate axons that have been induced to grow into an inappropriate geniculate layer have been revealed for light and electron microscopic study by being filled with horseradish peroxidase. After a unilateral ocular enucleation in kittens, single axons from the surviving eye show terminal arbors not only within their own geniculate layers but also in the denervated layers. The new, abnormal arbors arise from the terminal segments of arbors that lie within the nondenervated layer and make patterns of synaptic contacts that appear normal.

The terminal arbors of corticofugal axons to the dorsal lateral geniculate nucleus in the cat were filled with horseradish peroxidase and then partially reconstructed through serial sections. The results demonstrate that these arbors are far more complex than was suspected from previous studies of axon segments in individual sections. These axons branch profusely and spread widely within the nucleus. Within laminae A and A1 the terminal arbor of a single axon can be more than 800 micron wide compared with retinogeniculate axons whose terminal arbors range in width from 100 to 410 micron (Sur and Sherman, '82).

The posterior neocortex in the grey squirrel, Sciurus carolinensis, includes an extensive region which receives projections from the pulvinar. Previous studies have demonstrated that this cortical region can be subdivided on the basis of differences in cytoarchitecture and electrophysiologically defined representations of the visual field. The main purpose of the present paper was to determine whether these cortical subdivisions could be related to corresponding subdivisions in the pulvinar. The methods used to trace connections included anterograde degeneration, anterograde axonal transport of tritiated amino acids and the retrograde axonal transport of horseradish peroxidase. The results indicate that the pulvinar in this species contains at least three main subdivisions which can be distinguished by their cytoarchitecture and their patterns of connections. A caudal subdivision contains large, evenly-spaced neurons and receives bilateral input from the superficial, retinal-recipient layers of the superior colliculus. This caudal subdivision has reciprocal interconnections with a cytoarchitectonically distinct area in the temporal cortex. A rostro-lateral subdivision contains smaller, more lightly stained neurons which tend to form clusters. This subdivision receives only ipsilateral tectal input and projects to occipital area 18. This subdivision does not receive input from areas 17, 18, and 19, or from the temporal cortex. Finally, a rostro-medial subdivision is cytoarchitectonically similar to the rostro-lateral subdivision but receives little, if any, input from the superior colliculus. This rostro-medial area does, however, receive corticofugal projections from occipital areas 17, 18, and 19, and projects to area 19. These patterns of connections suggest that each of these subdivisions has close associations with the visual system. The question of whether similar subdivision are present in the visual thalamus of other species is discussed.

Results are reported of experiments designed to focus at attachment sites of inflammatory cells (ICs) on the luminal surface of brain endothelial cells (ECs) and on the mechanisms of horseradish peroxidase (HRP) transport across the altered blood-brain barrier (BBB) in a murine model of chronic relapsing experimental allergic encephalomyelitis. Cationized ferritin (CF) served as a marker for evaluating the electrostatic nature of brain microblood vessels (MBVs) on the plasma membranes of ICs or normal mouse peripheral white blood cells and erythrocytes. SJL/J mice demonstrating clinical illness were given HRP or CF, in vivo or in situ, respectively. Light microscopy and conventional transmission electron microscopy of cerebellum or thoracic and lumbar spinal cord regions demonstrated HRP leakage most pronounced in MBVs with perivascular infiltrates. HRP traversed across the ECs via numerous vesicles and tubular profiles located mostly in the parajunctional regions, while EC junctions appeared closed. Scanning electron microscopy demonstrated that IC attachment was primarily at parajunctional sites on the EC surface. We also observed increased microvillar projections extending from the EC surface into the lumen. CF demonstrated a patchy decoration on both the luminal EC surface and IC membranes but did not label uncoated invaginating membrane pits or tubular structures. Our data indicate that the points of attachment of the ICs on the EC surface may reflect specific receptor sites where the ICs eventually gain entrance into CNS across the BBB during brain inflammation.

Patterns of [3H]thymidine incorporation during neurogenesis of the embryonic chick retina have been compared in vitro and in ovo. Pieces of posterior, undifferentiated retinas were dissected from embryos on day 6 of incubation (E6) and cultured in the presence of [3H]thymidine. Label was added to the medium for 3 h on day 1, 2, 3 or 4 in culture. The retinas were fixed on the fifth day, embedded in epon, sectioned and processed for autoradiography. In parallel experiments, in ovo injections were made on embryonic day 6, 7, 8 or 9 (E6-E9). On E12 the embryos were fixed and a piece of the posterior retina from each eye was dissected and processed for autoradiography as above. Results show that the retinal explants develop well in culture and all of the layers of the neural retina differentiate. However, the cultured retinas are thinner than those grown in ovo. [3H]Thymidine labeling indicates that nearly all retinal neurons undergo their final mitotic divisions between E6 and E9. In addition the patterns of labeling in culture are similar to those in ovo. Most neurons, including the majority of cells in the ganglion cell layer and outer nuclear layer, are labeled on the first three days in culture and in E6-E7 embryos, while labeled cells are restricted to the inner nuclear layer in older specimens. Counts of labeled and unlabeled neurons in the ganglion cell layer suggest that the temporal pattern of neurogenesis in culture lags behind that in the embryo by about one day but that the spatial patterns of cell migration are the same.

Previous studies have shown that suturing one eyelid closed in a newborn kitten results in profound changes in the development of the visual system. Among these is a retardation in the growth of neurons in the layers of the dorsal lateral geniculate nucleus receiving retinal input from the closed eye. Moreover, the greatest effect appears to be in the largest neurons. The present study examines the effects of monocular deprivation on the perikaryal size of a select group of small lateral geniculate neurons. GABAergic neurons, that may be interneurons. These cells were selectively labeled by an antiserum to glutamic acid decarboxylase (GAD) and immunocytochemical methods. The results demonstrate that GAD+ neurons are among the smallest in the lateral geniculate nucleus and that they are insensitive to the effects of monocular deprivation. That is, GAD+ neurons in deprived laminae A and A1 are similar in size to those in the corresponding, nondeprived laminae. These findings are consistent with the hypothesis that GAD+ neurons are interneurons and therefore not subject to binocular competition in the visual cortex. This interpretation, however, is complicated by additional studies of the postnatal development of GAD+ neurons which reveal that GAD+ neurons grow to their adult size relatively early, before the onset of the critical period. Thus the insensitivity of the perikarya of GAD+ neurons to monocular deprivation may be attributable to their precocious growth.

The purpose of these experiments was to compare the synaptic organization of the subdivisions of the pulvinar defined in the preceding paper (Robson and Hall, '77) with each other and with the organization present in the dorsal lateral geniculate nucleus. The electron microscope was used to analyze normal synaptic arrangements and degenerating axonal terminals resulting from lesions. The dorsal lateral geniculate nucleus in the grey squirrel contains synaptic clusters similar to those described previously for other species. These clusters are characterized by large optic tract terminals which form multiple contacts onto large dendritic processes and other processes containing flat or pleomorphic vesicles. The geniculate lamina adjacent to the optic tract receives projections from the superior colliculus as well are from the retina. The terminals of the superior colliculus axons are small and medium sized and lie outside of the synaptic clusters. The retinal terminals are in the clusters. In the pulvinar, the rostro-medial subdivision contains synaptic clusters which resemble those in the lateral geniculate nucleus. These clusters contain large axon terminals which make multiple contacts onto large dendrites. However, these terminals are not contributed by an ascending sensory pathway but by axons from striate cortex. The rostro-lateral and caudal subdivisions of the pulvinar also contain synaptic clusters, but these clusters consist of a segment of a large dendrite which is ensheathed by medium-sized terminals. Since only a few of these medium sized terminals in any one cluster degenerate after tectal lesions, and none degenerate after cortical lesions, it is suggested that the morphological arrangement of these clusters may permit the convergence of axons from several sources, some of which are unidentified, onto the same dendritic segment.

The structural features of corticogeniculate axons were studied in adult cats after labeling them with horseradish peroxidase (HRP). Injections of HRP into the optic radiations near the dorsal lateral geniculate nucleus result in Golgi-like filling of both geniculate relay neurons and corticogeniculate axons. In the present material at least two main types of axons could be defined. The most common type is called the type I axon because it so closely resembles the type I axons described by Guillery ('66, '67) in Golgi preparations. These fine axons have smooth surfaces and consistent fiber diameter. Most terminal swellings are at the ends of short collateral branches and these swellings form asymmetric synaptic contacts onto small and medium-sized dendrites. Type I axons typically innervate more than one lamina as well as interlaminar zones and they clearly arise from the cerebral cortex. The second type of axon is called the beaded axon because of its numerous swellings, en passant. These swellings frequently are larger than those on type I axons and they differ from previously described corticogeniculate axon terminals in their ultrastructural features. That is, their synaptic contacts appear symmetrical and they form axosomatic contacts. Because of these differences, the possibility that beaded axons are of subcortical origin, particularly from the perigeniculate nucleus, is discussed. When type I axons and geniculate relay neurons are filled in the same region of the nucleus it is possible to identify probable sites of synaptic contact by using the light microscope. Such analyses indicate that corticogeniculate axons synapse directly onto relay cells, primarily on peripheral dendritic branches. Further, it appears that single axons contact many geniculate neurons and that single neurons are contacted by many axons.