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Stem and root of Lindera erythrocarpa were described and compared in the wood anatomical aspects. Root wood ap-pearedto differ from stem wood in the qualitative features of growth ring boundary, extraneous materials in vessel ele-ment and ray parenchyma cell, outline of ray, and sheath cell. In the quantitative features, there were differences be-tween these two tissues in vessels per square millimeter, tangential diameter of vessel lumina, length of vessel element, and width of ray. These wood anatomical differences between stem above ground and root below ground were thought to be attributed to their different growth environments.

High-yielding, stress-tolerant grass crops are essential to meet future food and energy demands. Efforts are underway to engineer improved varieties of the C3 cereal crop rice by introducing NADP-malic enzyme C4 photosynthesis using maize as a model system. However, several modifications to the rice leaf vasculature are potentially necessary, including the introduction of suberin lamellae into the bundle sheath cell walls. Suberized cell walls are ubiquitous in the root endodermis of all grasses, and developmental similarities are apparent between endodermis and bundle sheath cell walls. Nonetheless, there is considerable heterogeneity in sheath cell development and suberin composition both within and between grass taxa. The effect of this variation on physiological function remains ambiguous over forty years after suberin lamellae were initially proposed to regulate solute and photoassimilate fluxes and C4 gas exchange. Interspecies variation has confounded efforts to ascribe physiological differences specifically to the presence or absence of suberin lamellae. Thus, specific perturbation of suberization within a uniform genetic background is needed, but, until recently, the genetic resources to manipulate suberin composition in the grasses were largely unavailable. The recent dissection of the suberin biosynthesis pathway in model dicots and the identification of several promising candidate genes in model grasses will facilitate the characterization of the first suberin biosynthesis genes in a monocot. Much remains to be learned about the role of bundle sheath suberization in leaf physiology, but the stage is set for significant advances in the near future.

Malherbe and Chenantais1 are credited with the first report of pilomatricoma. In 1880, they described calcifying epitheliomas, initially thought to be tumors of the sebaceous glands. Malherbe corrected this view in 1905.2 Since then, this uncommon entity has been called “calcifying epithelioma of Malherbe.” After several studies suggested the cell of origin to be the outer sheath cell of the hair follicle, Forbis and Helwig3 in 1961 proposed the term “pilomatrixoma.” This new term was later corrected to “pilomatricoma,” which is more etymologically correct.4 Pilomatricoma is a benign skin neoplasm that usually presents as a single, slow-growing subcutaneous or intradermal nodule of less than 3 cm in diameter.5 It may appear at any age, with a bimodal peak in the first and sixth decades. The tumor is more common in females (female-to-male ratio of 1.5:1 overall but 2.5:1 in patients younger than 20 years).6,7 Anatomically, the head and neck is the favored site, representing more than 50% of its distribution.8

The fine structure of the numerous pores in the median body region of Xiphinema diversicaudatum females was observed by transmission electron microscopy. Each receptor has a characteristic number and arrangement of neurons. Two dendrites with the typical microtubule pattern 9×2, embedded within electron dense material, and representing the sensory system, are present in each receptor and extend into the tip of the pore. The pore contains a channel filled with amorphous material. Each pair of neurons is surrounded by two accessory cells, the socket and the sheath cell. Structural similarities with pores on the anterior part of the body of other phytoparasitic nematodes suggest that each pore represents a chemosensillum and may serve to monitor the environment.

Objetivou-se com este trabalho avaliar alterações nos caracteres anatômicos e morfológicos da folha (bainha e lâmina) e do caule de Brachiaria brizantha tratada com o regulador de crescimento trinexapac-ethyl. O delineamento experimental utilizado foi o completamente ao acaso, com duas doses do trinexapac-ethyl (0,00 e 0,75 kg ha-1) e cinco repetições. Cinquenta dias após a aplicação dos tratamentos, amostras do terço médio da bainha, da lâmina da segunda folha completamente expandida e do entrenó do caule abaixo da inserção da bainha foliar foram coletadas para a determinação de características morfológicas, como altura de planta, comprimento e diâmetro de entrenó, comprimento da bainha, comprimento e largura da folha. Para avaliação das características anatômicas, foram realizados cortes transversais da folha e do caule e cortes longitudinais do caule, em micrótomo de mesa, e corados com fuccina e azul de astra preparadas em lâminas semipermanentes. As imagens obtidas foram digitalizadas usando-se microscópio de luz acoplado a câmera digital e conectado a um computador. Para obtenção das medidas de área e medidas lineares foi utilizado o software Image Pro-Plus. Os dados foram submetidos à análise estatística, pelo teste F a 5% de probabilidade. O regulador de crescimento promoveu redução do comprimento do limbo foliar, do entrenó, da bainha e da altura de plantas. Por outro lado, no limbo foliar, o trinexapac-ethyl aumentou a espessura da lâmina foliar, da área das células da bainha e da área do mesofilo em B. brizantha. The objective of this work was to evaluate changes in the anatomical and morphological characters of leaf (sheath and mesophyll), and stem of Brachiaria brizantha when treated with the plant growth regulator trinexapac-ethyl. The experimental design was completely randomized, with two doses of trinexapac-ethyl (0.00, 0.75 kg ha-1) and five repetitions. Fifty days after treatment application, samples from the middle third of the sheath, blade of the second fully expanded leaf and stem internode below the leaf sheath insertion were collected for the determination of morphological characteristics, such as plant height, internode length and diameter, sheath length and leaf length and width. For evaluation of the anatomical features, transverse cuts of leaves, stem and sheath and longitudinal cuts of the stem were made, in table microtome and stained with fuchsin and astra blue and prepared into semi-permanent slides. The images obtained were scanned using a light microscope coupled to a digital camera and connected to a computer. To obtain area and linear measures, the software Image Pro-Plus was used. The data were subjected to statistical analysis, using the F test at 10% probability. The growth regulator reduced the length of tho the leaf blade, internode and sheath and also plant height. On the other hand, trinexapac-ethyl increased leaf blade thickness sheath cell and mesophyll areas, providing anatomical and morphological changes in B. brizantha.

A family of secreted proteins (the SXP/RAL-2 proteins) has been identified in animal parasitic nematodes and Caenorhabditis elegans. In this paper, we describe two full length cDNA sequences from the potato cyst nematode Globodera rostochiensis which could encode proteins similar to SXP/ RAL-2 proteins. We show that although both genes are expressed in second stage juveniles and in sedentary females of G. rostochiensis, they have remarkably different spatial expression patterns. The mRNA derived from one of the genes (gr-sxp-1) was present in the hypodermis, as has been described previously for one of these genes in an animal parasitic nematode. However, expression of the mRNA from the other gene was restricted to the gland cells surrounding the amphidial sense organs (the sheath cells). In addition to providing the first description of SXP proteins from a plant parasitic nematode, this work provides the first detailed characterisation of a protein secreted from the amphids of a plant parasite. Les protéines SXP/ RAL-2 du nématode à kyste de la pomme de terre Globodera rostochiensis : les protéines sécrétées par l'hypoderme et les amphides - Une famille de protéines sécrétées - les protéines SXP/RAL-2 - avait déjà été identifiée chez les nématodes zooparasites et chez Caenorhabditis elegans. Dans cet article nous décrivons deux séquences en longueur totale de cADN provenant du nématode à kyste de la pomme de terre Globodera rostochiensis, séquences qui pourraient coder des protéines similaires aux protéines SXP/RAL-2. Nous montrons que, bien que l'un et l'autre gène s'expriment chez les juvéniles de deuxième stade et chez les femelles sédentaires de Globodera rostochiensis, ils possèdent des profils d'expression spatiale remarquablement différents. Le rARN dérivé à partir d'un de ces gènes (gr-sxp-1) était présent dants l'hypoderme, comme cela avait déjà été décrit pour l'un de ces gènes chez un nématode zooparasite. Cependant, l'expression du mRNA de l'autre gène était limitée aux cellules glandulaires entourant les organes sensoriels amphidiens (les cellules de la gaine). Offrant la première description de protéines SXP provenant de nématodes phytopathogènes, le présent travail fournit de plus la première caractérisation détaillée d'une protéine sécrétée par les amphides d'un nématode parasite de plantes.

Recent advances in enzyme typing of root sheath cells have significantly increased the evidential value of hair examinations. However, arguably the majority of hairs examined in forensic science laboratories have no sheath cell material and attempts to individualise these hairs rely on detailed microscopic examination. It has been claimed that microscopy is highly subjective and that the variability of microscopic features is too great to allow individualisation of head hairs. This paper reviews a range of microscopic characters with suggestions aimed at improving the objectivity of hair examination which would allow large scale trials and the collection of population data to be carried out. Only then can a true evaluation of the worth of microscopic analysis of hair be made.

The hair-plate sensilla of the honeybee were examined by SEM and TEM. Apart from the normal single bristles, some were found with a threepronged point. The dendrite runs eccentrically within the cuticular canal. Below the socket septum it is enveloped by sheath cells 1 and 2. Sheath cell 2 also lines the remaining part of the cuticular canal and the subcuticular cavity continuous with the canal lumen. From sheath cell 2, abundant lamellae project into the canal system. The lamellae seem to have a double-unit membrane with a somewhat granular appearance.

Leaves harvested from unhardened and cold-hardened rye (Secale cereale L. 'Puma') were examined by electron microscopy. Upon cold acclimation,m mestome sheath cell walls were thickened asymmetrically toward the vascular bundle, while epidermal cell walls were thickened asymmetrically toward the leaf surface. Cell wall deposits were osmiophilic and lamellar in structure. These characteristics suggest deposition of lipid polymers. Epicuticular waxes also increased in thickness and changed from a rodlike to a platelet-like structure upon cold acclimation. Thickening of the epidermasl and mestome sheath cell walls during cold acclimation is thought to decrease injury caused by freezing or desiccation.

Following the Oschman and Wall technique, electron-dense structures (EDS) were found on unstained, unosmicated membranes of squid giant synapse axons. These densities contain high concentrations of calcium and phosphorus as identified by energy dispersive X-ray analysis. Based on the signal strength, the quantity is significantly greater than that of other regions of the membrane or tissue spaces. The calcium EDS occur as plaques or globules along the axonic membrane, and small globules are found between sheath cell processes. EDS also occur at the synaptic site. These densities were correlated with the opacity change seen in giant axons. It is proposed that these structures represent sites where the calcium-binding protein found by other investigators has become nearly saturated with calcium.

The peg sensillum, a type of sensillum intermingled with the long hair sensilla in the hair fields on the head of Locusta migratoria (Orthoptera: Acrididae), was studied by light, transmission and scanning electron microscopy. The peg sensilla have the features typical of contact chemoreceptors; each peg is innervated by 5 sense cells; and 4 of the dendrites, enclosed within a “dendritic canal”, pass through the central lumen of the peg to the distal part, below the apical pore. The 5th dendrite ends in a tubular body at the caudal side of the peg articulation. Each distal segment of the 5 dendrites has a ciliary structure (9 ×2+0) at the transition to the short proximal segment, which in each case turns to the side to merge with the soma of the bipolar sense cell. Four sheath cells are associated with the group of sense cells and they are surrounded by a 5th, special epidermis cell. The innermost (thecogen) sheath cell (No. 1) encloses the receptor-lymph space 1 and forms the cuticular sheath; sheath cells 2 and 4 form the boundary of the large volume of receptorlymph space 2. The number of sheath cells is discussed with reference to other insect sensilla and in a phylogenetic context.

Ultrastructure of the Johnston's organ was similar in both sexes of the black fly Simulium vittatum. Three types of scolopidia were found: types A, B, and C. Type A and B scolopidia are amphinematic and type C scolopidia are mononematic. Males had slightly wider pedicels than females and bore about 30 type A, 150 type B, and 4 type C scolopidia. Females had about 20 type A, 105 type B, and 5 type C scolopidia. The basic structure and location of each type are similar to, although less well organized than, these types in the adult mosquito. The number of type A and B scolopidia, while much lower than that found in mosquitoes, is similar to the number in other insects. Each amphinematic scolopidium has either two (type A) or three (type B) sensory cells, as well as three sheath cells and a long cuticular cap. A mononematic type C scolopidium has two sensory cells, a sheath cell, a short cap, and a microtubular cap cell. The structure of the Johnston's organ complements previous behavioural observations indicating that sound detection is absent or minimal in the black fly, even in the mate-seeking males. The probable function of each scolopidial type is discussed as it may relate to flying and wind detection.

The phasmid of infective second-stage juveniles of Heterodera schachtii consists of an external pore, cuticle-lined duct, socket cell, sheath cell, and single dendrite receptor. Specimens vary in detail and two discrete types, designated A and B, can be distinguished, with A being larger and relatively more complex. In both types of phasmids the socket cell is roughly cup shaped, envelops the duct, and partially encloses and forms junctional complexes with the sheath cell. The sheath cell fills the cup of the socket cell and occurs near the proximal end of the duct. In the A phasmid the sheath cell is deeply invaginated, forming a receptor cavity which is continuous with a maze of extracellular channels penetrating the cell; secretions accumulate in the channels and receptor cavity. Conversely, the sheath cell of the B phasmid lacks a receptor cavity and is nonsecretory. The sheath cell of both types of phasmid encloses and forms junctional complexes with a single dentritic process. In the A phasmid the process terminates within the receptor cavity whereas in the B type the tip is embedded within the sheath cell. A typical basal body or rootlets were not observed, although a ciliary region with a circle of eight doublets surrounding three or four singlets occurs slightly proximal to the terminus. Knowledge of phasmid structure of H. schachtii provides a basis for study of phasmid development and function in a plant parasite; it also contributes to understanding comparative morphology for phylogenetic analysis of Heteroderidae.

Conspicuous dilatations and inclusions of the rough endoplasmic reticulum have been observed within the cytoplasm of sheath cells (cells of Schwann) and connective tissue in cat sympathetic ganglia. The sheath cell inclusions have been found regularly in young animals (under 6 weeks of age), and in older specimens following partial preganglionic nerve section. Electron-density of the inclusion material is characteristic for each kind of cell.

The structure and innervation of the sensory setae which are present in large numbers on the penis of Balanus balanoides (L.) have been established by scanning and transmission electron microscopy. Each seta contains a small number of sensory dendrites surrounded by an extracellular supporting tube which is presumed to be secreted by the enclosing sheath cell. The dendrites, which distally extend beyond both the sheath cell and supporting tube, terminate at the tip of the seta within a pore-like invagination of the cuticle and thus are in direct contact with the environment. Proximally bundles of dendrites pass into the penis tissue where they are surrounded by several sheath cells. The supporting tube terminates at a point within the body of the penis where a series of intracellular rods arise. The ciliary character of the dendrites is evident in this region, the microtubules being organized into the (9 × 2) +2 pattern. It is deduced that the sensilla are chemosensory; their structure is compared with that of other crustacean sensilla which are presumed to be chemosensory.

That the spinal ganglion cells and sheath cells of Schwann have a common origin in the neural crest, his been accepted generally since Harrison's original experiments in 1904. When the dorsal portion of spinal cords of anuran embryos were removed (elimination of the ganglionic crest), the larvae lacked spinal ganglia and sensory nerves, and the motor nerves present were devoid of sheath cells. Recently Raven employing a different experimental approach assigns a cord origin to the sheath cells and claims that Harrison's conclusions were not justified, since in eliminating the neural crest he also destroyed the dorsal part of the spinal cord, thus not only removing such presumptive sheath cells as may originate there, but obstructing by deformation of the cord the dorsal migration of these elements which are supposed to lie in the ventral portion of this structure. Raven also concludes from his experimental results that sympathetic elements arise from both neural crest cells and from the ventral portion of ...

The geomagnetic field which is a part of the meteorological variables, is related to biological activities, especially to the orientation of microorganisms, insects, birds and fishes (Bamberger et al. 1978; Blackmore 1975; Brown et al. 1979; Chernyshev et al. 1978; Chervinets et al. 1979; Kirschvink 1981; Vilches-Troya et al. 1984; Wehner 1979). Variations in geomagnetic field have been correlated to congenital anomalies (Archer 1978; Archer 1979), psychological and convulsive disorders (Pokorny et al. 1966; Rajam et al. 1981), to the incidence of myocardial infarction (Bellossi et al. 1985; Knox et al. 1979), and to death rate variations (Feinleib et al. 1975). These variation can alter the growth and metabolism of cells (Kholodov 1964; Kopanev et al. 1979; Liboff et al. 1984; Shibib et al.; Sutherland et al. 1978). Because of the possible importance of biomagnetic phenomena in the nervous system, we developed experimental models to examine the effect of magnetic field variations on the cellular interactions of the developing nervous system of newborn rats.

In 1914, L. Bruns stated in Krause’s General Surgery of Brain Disorders that brain tumors include all neoplasias growing within the cranium and that they comprise three groups: (1) true tumors, (2) infectious granulomas, and (3) parasites. Current usage is more precise and is limited to the first of Bruns’ categories. Even so, brain tumors constitute a large and very heterogeneous group. A taxonomic approach to classification is necessary if we are to make sense of an initially disorganized set of observations, compare the findings of different observers, and attempt a prognostic evaluation.

Cavanagh J.B. & Nolan C.C. 1982 Neuropathology and Applied Neurobiology 8, 465–476 The effects of acrylamide on β-glucuronidase and acid phosphatase activities in rat sciatic nerve above and below a ligature The enzymes β-glucuronidase and acid phosphatase have been assayed by histochemical and by fluorimetric methods above and below a tightly tied ligature on the rat sciatic nerve over the subsequent 10 days. These findings have been compared with similarly treated animals also given four daily doses of acrylamide (50 mg/kg). The following have been found: 1 during this time, acrylamide at this dose causes slight increases in β-glucuronidase in untied sciatic nerves, detectable both histochemically and fluorimetrically; 2 below the ligature both enzyme activities were greatly increased and this was slightly reduced in the acrylamide-dosed animals; 3 there was a mild rise in β-glucuronidase activity in the 10 cm above the ligature in undosed animals demonstrable both histochemically and fluorimetrically; 4 that in the acrylamide-dosed animals there was a marked rise in β-glucuronidase activity both 10 cm and 20 cm above the ligature which was intensified at 7 days and at 10 days after dosing. This was demonstrated both histochemically and fluorimetrically. These results are discussed in the light of the known sheath cell and axonal responses to acrylamide intoxication.

The distribution of pit fields and plasmodesmata in the mestome-sheath cells of a wheat leaf has been determined by study of sections and partial macerates. Each bundle is approximately symmetrical about the sagittal plane and most plasmodesmata occur in the mestome sheath where its cells abut the metaphloem. Plasmodesmata are absent adjacent to xylem vessels, and the frequency of plasmodesmata declines sharply in cells that lie close to the sagittal plane. Calculations show that 1 cm(2) of leaf lamina has approximately 2x10(8) plasmodesmatal connections to the phloem of the longitudinal veins, and that 85% of these connections are to the late-maturing intermediate bundles that do not complete their differentiation until leaf growth is nearly finished. The phloem area of inner tangential wall of the mestome sheath amounts to 0.26 cm(2) per cm(2) of leaf area and plasmodesmata occupy 1.5% of this area.These anatomical facts are used to estimate the sugar flux across the inner-tangential wall of the sheath as 2x10(2) pmol s(-1) cm(2) sheath. Further analysis strongly suggests that this flux must cross the sheath by diffusion through the plasmodesmata, creating there a flux of 1.5x10(4) pmol s(-1) cm(-2) plasmodesma. These results are compared with data recently obtained for the transfer-cell/sieve-element boundary in Vicia and are found to be about one tenth of the flux in that system, the transfer being adequately driven by a concentration gradient of 50 μg cm(-3) of sugar across the sheath. Such a concentration gradient could be achieved by the photosynthetic activity of about 50 chloroplasts acting for about 2 min. The transverse veins that lack a mestome sheath are unlikely to account for more than 10% of the fluxes calculated here and have been ignored in the calculations. It is concluded that the symplastic pathway is the only possible one for assimilate traffic across the mestome sheath in wheat, and that diffusion down a gradient of sugar concentration from the chloroplasts to the sheath acts as the driving force. This suggestion is reinforced by analysis of the contributions of the larger and smaller veins to the water flux from the same square centimetre of leaf. This analysis shows that 99% of the water flux must exit from the xylem of the 7 large bundles, presumably through the apoplast, securing an effective separation between the inwardly directed flow of sugar (laoded symplastically chiefly through the small longitudinal bundles) and the outwardly directed, very much larger flux of water.

The anterior neurosensory organs of the larvae of the soybean cyst nematode consist of two amphidial receptors, six inner and four outer labial receptors, four cephalic receptors, and two types of accessory receptors. Each receptor has a characteristic number and arrangement of cilia. Seven cilia are present in the canals of each amphidial receptor, two in each inner labial receptor, and a single cilium in each of the outer labial and cephalic receptors. The ciliary portion of the two types of accessory receptors are located laterointernal and lateroexternal to the amphidial canal. The cilia of the inner accessory receptors have their basal regions just below the cephalic framework, whereas, the basal regions of the cilia of the outer accessory receptors merge with the basal regions of the amphidial canal cilia. Some of the outer accessory receptor cilia branch as they ascend toward the cephalic framework. Both types of accessory receptors form swollen ciliary terminals that extend into the various sectors of the cephalic framework. The intermembrane spaces of the inner accessory receptors are electron lucent while spaces formed by the cilia in the outer accessory and other receptors are filled with electron-dense deposits. Ventral and posterior to the axons supporting the amphidial canal cilia is a microvillar nerve process that extends into the amphidial sheath cell. Each nerve process axon terminates in a pair of stout cilia. The membrane of the axon that gives rise to these cilia evaginates to form numerous microvilli that characterize this nerve process. Physical locations and functional roles of these receptors are discussed.

This chapter concerns mainly the gross and microscopic aspects of normal cerebral development during the second half of gestation, that is the period usually encountered by the pathologist. Its purpose is to provide a frame of reference for assessing normalcy in the brain of the fetus and of the newborn, to point out changes of borderline significance, and to establish base lines for the evaluation of gross or microscopic pathologic changes. The chapter does not provide an extensive review of normal embryology of the human central nervous system; developmental principles are cited only to the extent to which they are of help in interpreting abnormal tissue structure, and pertinent data are generally included in the respective chapters of the text.

Loss of cells and failure of axons from surviving neurons to elongate through damaged CNS tissues are common consequences of injury to the brain and spinal cord. Recent animal experiments using neural or sheath cell transplants have been aimed at replacing the lost or impaired cells and also at promoting and directing the growth of neuronal processes. In this review we survey some of these studies with particular emphasis on the influence of the glial environment on axonal growth.