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Biomedical subjects

V Chan-Palay

Publications and source records attributed to V Chan-Palay.

At least 91 records · Page 5Linked to original sources
PubMed1977

Immunocytochemical identification of substance P cells and their processes in rat sensory ganglia and their terminals in the spinal cord: light microscopic studies.

The indirect immunofluorescence method and the unlabeled primary antibody peroxidase antiperoxidase method are used to demonstrate the substance P (SP) plexus in the spinal cord and SP cells in the sensory ganglia of the rat. The normal untreated and the control side of the dorsal rhizotomized rat show vast SP immunoreactive plexuses in the substantia gelatinosa, central gray, and ventral gray regions of the spinal cord. In each sensory ganglion, approximately 250 SP immunoreactive cells are found singly or in small groups of 2 or 3, near blood capillaries or among ganglion and satellite cells. They contain intensely immunoreactive cytoplasmic granules 0.1-3.0 mum across. Occasionally, free intensely immunoreactive granules are found in the surrounding tissue near an SP cell but not clearly within the confines of the cell. Another type of immunoreaction has been observed with both methods. A less intense, homogeneous reactivity has been found in lamellae insinuated between ganglion cells and near blood capillaries close to an SP cell; the characteristic disposition of this homogeneous reactivity suggests an extracellular location. Unilateral rhizotomy results in an increased number of immunoreactive SP cells and nerve fibers as well as a more extensive homogeneous immunoreactivity. These results add to existing evidence that SP cells in sensory ganglia send fibers via the dorsal roots to the spinal cord. SP cells, fibers, and terminals do not take up exogenously applied (125)I-labeled [Tyr(8)]SP and cannot be demonstrated by subsequent autoradiography. No neurotensin immunoreactive cells were found in sensory ganglia.

Animals↗
PubMed1977

Ultrastructural identification of substance P cells and their processes in rat sensory ganglia and their terminals in the spinal cord by immunocytochemistry.

The unlabeled substance P (SP) antibody-peroxidase-antiperoxidase reaction was used on tissue prior to embedding in epoxy reins for ultrastructural identification of the SP cell and its immunoreactive granules. The SP cell is 10-20 mum in diameter and has sparse cytoplasm with numerous intensely reactive SP granules 100-300 nm across, large clear vacuoles, elaborate smooth endoplasmic reticulum, fragmentary rough endoplasmic reticulum, dispersed ribosomes, few mitochondria, and a modest Glogi apparatus. The large SP-reactive granules are discharged into the extracellular space, either with cell membrane intact or as unbound dense material. The membrane-bound dense granucles are transported intact through endothelial cells into the blood or are picked up by Schwann cells and fibroblasts. Other SP-reactive granules lose their limiting membranes, fragment, and then disperse into fine immunoreactive grains that bind to the extracellular matrix and to collagen. Dispersed SP-reactive granules are transported within myriad pinocytotic vesicles across endothelial cells with numerous luminal plications and are discharged into the blood. Pinocytosis of dispersed SP-reactive material, that can be detected intracellularly, also occurs in Schwann cells and fibroblasts. The SP axons to the substantia gleatinosa are unmyelinated or finely myelinated. Their synaptic varicosities display a generalized axoplasmic immunoreactivity, which also occurs in and around small vesicles. The larger SP synaptic vesicles are intensely reactive.

Animals↗
PubMed1976

Afferents to the cerebellar lateral nucleus. Evidence from retrograde transport of horseradish peroxidase after pressure injections through micropipettes.

HRP was injected by pressure from glass capillary micropipettes unilaterally into the lateral nucleus of rat so as to encompass the entire nucleus, but without spread into the interpositus nuclei. The cells of origin of the afferents to the lateral nucleus were studied after retrograde transport of the HRP. The reticulotegmental nucleus of the pons was labelled bilaterally and is the major source of crossed and uncrossed reticular imputs. The pontine nuclei also provide extensive crossed and uncrossed afferents. The inferior olive gives a large crossed olivo-lateral nucleus projection and a minor uncrossed input. The trigeminal nuclear complex--the nucleus of the spinal tract and the mesencephalic, principal sensory, and motor nuclei--all provide uncrossed afferents. The rostral portion of the lateral reticular nucleus gives a small crossed and uncrossed projection while the perihypoglossal nuclei and the dorsal parabrachial body give crossed afferents to the lateral nucleus. The norepinephrine afferent system from the locus coeruleus is represented by one or two heavily labelled cells and the serotonin raphe systems come from at least five raphe subgroups, the dorsal, superior centralis, pontis, obscurus and magnus nuclei. No evidence was found for commissural fibers between ipsilateral or contralateral cerebellar nuclei, or afferent axons from the spinocerebellar nuclei and the paramedian retricular nucleus. The significance of these sources of afferent imputs to the lateral cerebellar nucleus is discussed. The question is raised of the direct relationship between size of terminal axonal arborization and the quantity of HRP granules present in a cell retrograde transport. The limitations of the HRP method for detecting subtle local differences in the distribution of afferents within the heterogeneous groups of neurons in the lateral nucleus are discussed.

Animals↗
PubMed1976

Serotonin axons in the supra- and subependymal plexuses and in the leptomeninges; their roles in local alterations of cerebrospinal fluid and vasomotor activity.

Extensive plexuses of serotonin axons form a supra- and subependymal system in the walls of the ventricles, in the arachnoid sheath around major cerebral blood vessels, and in the pia over the spinal cord. These have been demonstrated by autoradiography after continuous intraventricular perfusions of exogenous [3H]5-HT in rats and monkeys. The axons accumulate 5,6-DHT rendering them electron opaque, but have no uptake systems for [3H]NE. After treatment with MAO inhibitors and [3H]5-HT, the axonal boutons contain large (70nm) variably dense synaptic vesicles, and small (35 nm) vesicles each equipped with a dense dot. The latter vesicles are not seen in untreated controls. Electrical stimulation in the raphe nuclei causes significant increases in axonal [3H]5-HT uptake indicating that the fibers originate in the raphe. Quantitatively, the supraependymal plexus is variable, profuse over the dorsal and ventral aqueductal surfaces, sparse over the lateral aspects. Individual raphe neurons have their specific uptake affinities for [3H]5-HT that are independent of tracer concentration or diffusion gradient. It is suggested that raphe neurons with low 5-HT uptake may utilize other neurotransmitters. Two new functional roles are proposed: (1) the serotonin ventricular and pial axons are probably important modifiers of local cerebrospinal fluid (CSF) composition so that regional CSF variations in 5-HT and its metabolites are highly probable; (2) the subarachnoid plexus around major cerebral vessels may contribute to local vasomotor action, thus affecting the cerebral blood flow. The possible significance of these serotonin systems for an understanding of certain neurological entities such as migraine and hemodynamic regulation in cerebral vascular disease is indicated.

5,6-Dihydroxytryptamine↗
PubMed1976

A guide to the synaptic analysis of the neuropil.

A morphological analysis of the organization of the gray matter in the central nervous system depends on the discovery of consistent repetitive patterns. Without these, the gray matter remains a chaotic jungle. An hypothesis derived from the study of a few simple regions has been developed to serve as a guide in finding these patterns. It states that all nerve fibers and terminals arising from a particular group of nerve cells, or, more precisely, a particular nerve cell type, display similar axoplasmic configurations despite variations in size and shape of the terminations. This hypothesis is reminiscent of the so-called Dale's principle that a nerve cell makes use of the same transmitter at all of its branches or terminations. These apparent rules of uniformity or congruity merely reflect the functional integrity of the nerve cell and the role of its parts in the nervous system. But as an hypothesis, it needs to be tested, and it needs to be tested anew in each region, since exceptions to the assumed rule can be expected. It is therefore proposed as the first working hypothesis in each new region. If it should prove to be true in general, it will facilitate and rationalize the analysis of the gray matter, as it has already done in the cerebellar cortex and the deep cerebellar nuclei. If it should prove to be false in a few regions, the analysis will become more difficult, and additional modes of marking nerve endings will have to be used. Experimental methods for identifying nerve terminals can be translated from the light microscopic to the electron microscopic level, but there are significant drawbacks at both levels: lack of precision, destruction of fibers of passage, and rapid evolution of the degenerative process may greatly restrict their usefulness. Labeling with tritiated amino acids or transmitters, or with horseradish peroxidase, provide new methods for tracing interneuronal connections at the electron microscopic level. These have the advantages of high specificity, nondestructiveness and a physiological mode of selective marking. However, they do not offer a solution to the problem of short-range connections. For these, careful reconstructions of serial sections may prove necessary, as Sjöstrand (1974) has demonstrated in a remarkable paper on the retina. The aim of all these methods is to discover patterns of synaptic connectivity in order to map the cellular organization of the nervous system. In the foregoing, nothing was said about synapses other than those articulating axons with somata or dendrites and their appendages. Clearly the same principles of recognition apply to axo-axonal and dendro-dendritic synapses. Although the synapses that have been considered here are chemical synapses, the same questions regarding the identity of the partners in electrotonic junctions must be asked as well.

Amino Acids↗
PubMed1975

Fine structure of labelled axons in the cerebellar cortex and nuclei of rodents and primates after intraventricular infusions with tritiated serotonin.

The cerebellar cortex and deep cerebellar nuclei in rats and rhesus monkey were studied after treatment with monoamine oxidase inhibitor and continuous intraventricular infusion with 10(-5) M serotonin-3H. Autoradiographs were prepared for light and electron microscopy. The cerebellum contained no labelled cells. Labelled unmyelinated axons arrive from the brain stem via the periventricular zones of the aqueduct and fourth ventricle. In the parafloccular cortex about 1 per cent of the mossy fibers are labelled, together with a small number of fine varicose axons in the molecular layer that run parallel to the folial axes (less than 0.1%). In the paravermal and vermal cortex there are few labelled fibers in the granular layer and a five-fold greater number of labelled axons in the molecular layer (about 0.5%). Apparently three systems of serotonin-containing axons are present in the cortex: mossy fibers, parallel fiber-like, and a diffuse system in granular and molecular layers. The fastigial (medial), interpositus, and dentate (lateral) nuclei, lateral vestibular and other vestibular nuclei all have numerous labelled axons. The dentate and interpositus nuclei receive labelled fibers which arrive through the superior cerebellar peduncle as well as from the periventricular area. Six morphologically different classes of labelled axon terminals have been differentiated. Class 1a, the mossy fiber rosettes, and class 1b, the CAT2 axons, have small, round, clear synaptic vesicles and large granular vesicles (lgv); class 2 axons have a distinctive collection of round granular vesicles; class 3 boutons have numerous tubular profiles, a few containing dense dots, packed in a dark axoplasmic matrix; class 4 axons have tiny 250 A granular vesicles, clear tubular profiles and occasional LGV; class 5 terminals have numerous LGV, both round and elongated, with clear round and tubular profiles; class 6 terminals have LGV, clear and granular synaptic vesicles and clear tubular profiles. All these axons have LGV 900 A in diameter with 500-600 A variably dense centers that do not fill the vesicle, and Gray's type 1 axodendritic or axasomatic synapses on postsynaptic locations in the cortex and nuclei. Labelled axons in the cortex end as mossy fibers upon granule cell dendrites in glomeruli (Class 1a) or upon dendrites of cortical interneurons, e.g. Golgi cells, basket and stellate cells, and not on Purkinje cells. ...

Animals↗
PubMed1975

Cytoplasmic inclusions of neurons in the monkey visual cortex (area 19).

Several unusual neuronal inclusions were found in certain cells of the rhesus monkey visual cortex (Area 19): 1. Filamentous bodies, present in the small stellate cells of layer IV, globoid, 0.3-0.6 mum in diameter, consisting of fine 50 A filaments in a hexagonal meshwork. These are often associated with the labyrinthine bodies. 2. Labyrinthine bodies found exclusively in the small stellate cells of layer IV, including certain neurons with dispersed ribosomes. These are 0.4-0.7 mum in diameter and consist of 900 A wide tubes which interconnect with one another. The walls of these tubes are continuous and made up of a sheet or honeycomb lacework of small hexagonal 150 A subunits. 3. This inclusion, an aggregate 0.3-0.7 mum in size, consists of small membrane-bounded vesicles with a single dense granule associated with other non-membrane bound small dense droplets. The inclusions are always associated with the maturing face of the Golgi complex of certain layer IV pyramidal cells; as such, they may be an unusual product of the Golgi apparatus. These observations were confirmed by examination of stereo pairs of electron micrographs. Speculations are made with regard to possible functions for these inclusions.

Animals↗
PubMed1974

A review of lamination in area 17 of the visual cortex Macaca mulatta.

This paper develops a concordance of methods for designating laminae in the primate striate cortex. The classic notation schemes of Ramón y Cajal, Brodmann, and von Bonin and four recent modifications are described in words and photomicrographs. The recent trend toward adopting a lamination scheme that effects a division of cells into recognizable layers and at the same time reflects their connections is considered. Since a single, consistent plan for lamination of the visual cortex would facilitate communication among investigators, it is suggested that Brodmann's original scheme be followed as the most generally useful and applicable.

Animals↗
PubMed1974

Meynert cells in the primate visual cortex.

The solitary cells of Meynert are distinguished by their specific location in layer V of the striate cortex, very large size, argyrophilia, and the profusion of neurofilaments in their dendrites and perikarya. They occur with greater frequency in the macular region of the cortex, spaced a minimal distance of 110 mum apart, at a maximum density of about 8000/cm-2. In the perifoveal cortex, Meynert cells are spaced about 400 mum apart and packed at a density of approximately 625/cm-2. Each Meynert cell has an apical dendrite and many large basal dendrites. The perikaryon and primary segments of all dendrites are spine-free; however, more distally a total of 36 000 spines are present, differentially disposed upon the dendritic surfaces. The basal dendrites bear over 77% of the spines on the Meynert cell, although they account for only 66% of the total length of the dendritic arborization. The first part of the apical dendrite is the most densely decorated with appendages, accounting for almost 10% of the spines on the whole dendritic tree. The apical dendrite becomes progressively less spiny as it passes through the superficial part of layers IV and III; less than 2.5% of the total number of spines of the Meynert cell project from this part of the apical dendrite. When the dendrite reaches layer II it bursts into an umbel of rapidly tapering branches. These are highly spinose, accounting for 8-13% of the cell's total, dispersed over only 23% of the linear dendritic length. It is suggested that this differential distribution of thorns can be correlated with the axonal inputs in the various cortical layers, and that the Meynert cell is designed to receive maximal information from layers I and II, and from layers V and VI, which are sources mainly of intracortical inputs. Thus the Meynert cell may be principally concerned with integrative information. In the perifoveal cortex, the basal dendrites of adjacent Meynert cells overlap considerably, and the apical terminal bouquet dendrites do not. In the macular cortex, because of the increased frequency of these neurons, both basaal and apical terminal dendritic fields overlap. A model is developed to illustrate these hypotheses.

Animals↗
PubMed1974

Neuronal perikarya with dispersed, single ribosomes in the visual cortex of Macaca mulatta.

Numerous small and medium-sized neuronal perikarya in layers III and IV of the visual cortex display an unusual pattern of ribosomal distribution. Instead of being aggregated in clusters, spirals, rows, and other regular polysomal configurations, the ribosomes, whether free or attached to the endoplasmic reticulum, are randomly dispersed, with no discernible pattern. The endoplasmic reticulum in such cells is reduced to a few (perhaps only one) meandering, broad cisternae, which delimit broad fields of cytoplasmic matrix occupied almost solely by scattered, single ribosomes. The Golgi apparatus is elaborate. Mitochondria are either small and numerous or large and infrequent. The other organelles, including the nucleus and nucleolus, are not remarkable. Axonal terminals synapse in the normal fashion on the surfaces of these cells and their dendrites. Associated with these cells are more numerous intermediate cells in which a few to many polysomal clusters can be found. It is proposed that the neurons with dispersed, single ribosomes are inactive in protein synthesis and that the suspension of such an important metabolic activity is probably temporary. Thus, these cells are considered to be part of a population undergoing cyclic fluctuations in the intensity of protein synthesis that should be correlated with their specific neural behavior.

Animals↗