摘要:

AbstractThe cat hypoglossal nerve and nucleus have been used as a model for the study of the occurrence and time course of modifications in the size and composition of the perineuronal glial cell population as they relate to cytological changes in the nerve cell body and the initiation and progress of axon regeneration. Animals were killed at 2, 5, 10, 20, 35, 65, and 115 days after crush injury to the hypoglossal nerve. At 5 days after surgery, growth cones and regenerating unmyelinated axons were present at the lesion site, but no conspicuous changes were apparent in the nerve cell bodies. At 10 days after surgery, the granular endoplasmic reticulum was disaggregated and depleted. The elongation phase appeared to be completed at 20 days, as judged by the bilateral retrograde labeling of the hypoglossal nuclei with horseradish peroxidase. By 35 days, the cytoarchitecture of the nerve cell bodies and maturation of axons, as determined by a comparison of the relative frequency distribution of cross sectional areas proximal and distal to the lesion, were completely restored. Comparative quantitative light microscopic examination of the hypoglossal nuclei of intact and experimental animals failed to reveal any statistically significant differences in the total number of glial cells, number of glial cells/unit area of neuropil, or relative proportions of glial cell types at any of the postoperative time intervals. Moreover, electron microscopic quantitation of the microglial cell population did not reveal any significant alterations in the number, density, location, or morphology of these cells. These results demonstrate that perineuronal glial cell proliferation or changes in the composition of the glial cell population are not attendant on retrograde changes in the cat hypoglossal nucleus or a necessary concomitant to successful axon regeneration.

ISSN:0092-7317    

DOI:10.1002/cne.902330402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractNeurogenesis in the ventricular layer and the development of cell topography in the ganglion cell layer have been studied in whole‐mounts of human fetal retinae. At the end of the embryonic period mitotic figures were seen over the entire outer surface of the retina. By about 14 weeks gestation mitosis had ceased in central retina and differentiation of photoreceptor nuclei was evident within a well‐defined area which constituted about 2% of total retina area. This area was approximately centered on the site of the putative fovea, identified by the exclusive development of cone nuclei at that location. The area of retina in which mitosis had ceased increased as gestation progressed. By mid‐gestation mitosis in the ventricular layer occupied about 77% of the outer surface of the retina and by about 30 weeks gestation mitosis in the ventricular layer had ceased. Cell density distributions in the ganglion cell layer were nonuniform at all stages studied (14–40 weeks). Densities were highest at about 17 weeks gestation, and by mid‐gestation the adult pattern of cell topography was present with maps showing elevated cell densities in posterior retina and along the horizontal meridian. Cell densities generally declined throughout the remainder of the gestation period, except in the posterior retina, where densities in the perifoveal ganglion cell layer remained high during the second half of gestation. There is a rapid decline in cell density in the foveal ganglion cell layer toward the end of gestation, and it is suggested that the persistence of high densities in the perifoveal region may be related to migration of cells away from the developing fovea. The total population of cells in the ganglion cell layer was highest (2.2–2.5 million cells) between about weeks 18 and 30 of gestation. After this the cell population declined rapidly to 1.5–1.7 million cells. It is suggested that naturally occurring neuronal death is largely responsible for

ISSN:0092-7317    

DOI:10.1002/cne.902330403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe distribution of neuronal elements containing immunoreactive somatostatin (I‐SRIF) in the rat central visual pathway was examined by light‐microscopic immunocytochemistry. These studies were concerned with the location and morphology of neurons and innervated cells and the distribution of fiber and terminal plexuses in the primary visual cortex (area 17), visual association areas 18 and 18a, the superior colliculus, the lateral geniculate nucleus, and the pretectum.In the superior colliculus, I‐SRIF‐containing fibers and perikarya were distributed predominantly in the superficial, or visual, layers; these elements were moderately dense and occupied the entire mediolateral extent of these layers. In the intermediate and deep layers, immunoreactive neurons were widely scattered, and fibers were located mainly in the medial third. Immunoreactive cell populations in the superior colliculus included small bipolar neurons with fusiform perikarya and multipolar neurons with round to ovoid perikarya. In the pretectum, the peptide was demonstrable in large and small multipolar neurons of the nucleus of the optic tract and in the posterior and olivary pretectal nuclei. I‐SRIF‐containing neurons were also present in the nucleus of the posterior commissure, the nucleus of Edinger‐Westphal, and the ventral division of the lateral geniculate nucleus. In the visual cortex, the peptide was present in all layers and in a variety of morphologically defined cell populations, including some which are presumed excitatory (pyramidal and bipolar cells) and others which are presumed inhibitory (bitufted and stellate cells).Our data suggest that somatostatin is involved in visual and visuomotor reflex pathways and in the horizontal optokinetic nystagmus reflex pathway. These results provide a foundation for further studies to evaluate the role of this peptide in vis

ISSN:0092-7317    

DOI:10.1002/cne.902330404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe innervation of the auditory organ of the alligator lizard is described. Patterns of distribution of the nerve fibers were studied at the light microscopic level with the horseradish peroxidase technique, and the types of synaptic contacts with hair cells were studied at the transmission electron microscopic level with standard techniques. The innervation of the two regions of the basilar papilla differs in the following ways. In the apical region, some fibers send branches along the length of the basilar papilla, and both afferent (non‐vesiculated) and efferent (vesiculated) nerve endings are present. In the basal region, all fibers terminate in the immediate area where they enter the papilla without sending branches along the length of the papilla; efferent endings are lacking, and nerve fibers are of a smaller average diameter. The punctate nature of the innervation of hair cells in the basal region is consistent with the hypothesis that the systematic organization according to frequency sensitivity observed in electrophysiological recordings from basal nerve fibers may be related to the length of the stereocilia on the hair cells with which the nerve synapse

ISSN:0092-7317    

DOI:10.1002/cne.902330405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractGolgi techniques were combined with electron microscopic autoradiography to identify four subpopulations of amacrine cell in the cat retina which accumulate (3H)glycine. These subpopulations include types A3, A4, A7(AII), and A8 amacrine cells. All are narrow‐field cells with dendritic spreads of less than 100 μm. Quantification of silver grains showed that each subpopulation exhibits a consistent affinity for (3H)glycine. Type A8 cells were found to have the greatest affinity with normalized grain densities of 0.88–1.0 grains/μm2on a scale in which 1.0 represents the most heavily labeled cell. Type A4 cells were moderately labeled with grain densities ranging from 0.40 to 0.68 grains/μm2. A7(AII) and A3 amacrines were lightly labeled with grain densities of 0.33–0.35 grains/μm2and 0.28–0.30 grains/μm2,

ISSN:0092-7317    

DOI:10.1002/cne.902330406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractPositions, numbers, and cell and nuclear sizes of mesencephalic fifth nucleus (M‐V) cells were determined inXenopus laevislarvae in stages 47 through the end of metamorphosis at stage 66. M‐V cells may be found at every tectal level, from the rostralmost section almost to the caudal pole, and in the anterior medullary velum. A large majority of the cells lie between 15 and 65% caudad of the rostral tip of the tectum. At anterior and middle tectal levels the cells lie lateral to but mainly above the optic ventricle. At posterior levels, to which the ventricle does not extend, a few cells may be seen at middle and lower tectal levels, as if in transition to the anterior medullary velum. At stage 47 fewer than ten cells are seen in each animal. The numbers rise to 20–40 by stage 50, and are uniformly above 100 after stage 51. Initially many M‐V cells were small, i.e., 6–7 μm in diameter, but grew to a mean diameter of about 19 μm at stage 59, with a maximum value of 29 μm. A single individual at stage 57 had 581 cells. The peak of mean cell numbers 387, occurred at stage 59, which was also the stage with the highest mean values for nuclear and cell sizes. Pyknotic M‐V cells at low frequency were seen at stages 55 and 57, and at all stages thereafter. Cell death frequency peaked at stage 62, but continued through stage 66. By stage 66 mean cell numbers had been reduced to about 240, indicating survival of about 60% of cells prese

ISSN:0092-7317    

DOI:10.1002/cne.902330407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractIn the medial and commissural subdivisions of the nucleus tractus solitarii enkephalin and substance P immunoreactivities were localized within synaptic terminals, unmyelinated axons, and neuronal cell bodies. Both enkephalin and substance P immunoreactivities were contained within synaptic terminals which had a mixture of small clear vesicles and dense core vesicles. The presence of dense core vesicles within both the enkephalin‐and substance P‐immunoreactive terminals was a consistent feature, although they were not associated with the actual synaptic junction. While enkephalin‐ and substance P‐immunoreactive terminals shared a similar morphology, their respective distributions along the dendritic tree were quite distinct. Enkephalin‐immunoreactive terminals contacted mainly the cell body and proximal portions of the dendritic tree. In contrast, substance P‐immunoreactive terminals synapsed predominantly with spines and shafts of small to medium‐sized dendrites. Few substance P‐immunoreactive terminals contacted proximal dendrites and they were never presynaptic to the neuronal cell body. This apparent segregation of synaptic terminals on neurons suggests that enkephalin synapses have a more pronounced effect than substa

ISSN:0092-7317    

DOI:10.1002/cne.902330408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractTo investigate the development of the subretinal space in the human infant, eyes were obtained from 12 live‐born, anomaly‐free, preterm infants from 20 to 32 weeks gestation and from one 3‐month postterm infant. The retinas were studied by light microscopy, electron microscopy, and immunocytochemistry. The immunocytochemical studies utilized rabbit antiserum against purified bovine interstitial retinol binding protein (IRBP). A subretinal space containing IRBP was present in the central retina at 20 weeks and extended further into the periphery (expressed as a percentage of the distance from the optic disc to the ora serrata in the temporal hemisphere) as the retina developed. At 28 weeks, IRBP was absent only from the most peripheral 25% of the retina and reached the temporal ora serrata at 32 weeks. At 3 months postterm, IRBP immunofluorescence outlined fully developed photoreceptors, which were present from the optic disc to the ora serrata. The appearance of IRBP in the subretinal space correlated with the development of the first photoreceptor outer segment

ISSN:0092-7317    

DOI:10.1002/cne.902330409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe occurrence, distribution, and origin of immunoreactive calcitonin gene‐related peptide (CGRP) in nerves of rat, guinea pig, cat, and monkey eyes were investigated by immunocytochemistry, radioimmunoassay, and chromatography. A rich network of CGRP‐immunoreactive nerve fibres was noted in the anterior uvea, which was widely distributed in both dilator and constrictor papillae muscles and extended to the ciliary body and uveal blood vessels. Numerous CGRP‐immunoreactive neuronal cells were present in the trigeminal ganglion. The extractable CGRP was 8.6 ± 1.8 pmoles/gm of tissue in the iris and 44.0 ± 8.1 pmoles/gm in the trigeminal ganglion. Following damage to the Gasserian ganglion a marked decrease of CGRP immunoreactivity was observed in the anterior uvea (control 11.3± 1.6 pmoles/gm; operated 1.4 ± 0.1 pmoles/gm) confirming the origin of the immunoreactive fibres from trigeminal primary sensory neurons. The sensory nature of the CGRP‐immunoreactive fibres was substantiated by the depletion of CGRP immunoreactivity observed after treatment with capsaicin, which is known to cause selective degeneration of sensory neurons. Comparative studies on the distribution and colocalisation of CGRP and the putative sensory neurotransmitter substance P revealed a closely parallel distribution of the two peptides in certain regions of the uvea and their coexistence in a subpopulation of trigeminal primary sensory neurons. This study suggests that the sensory nervous system in the eye is more heterogeneous in terms of its putative neurotransmitters than previousl

ISSN:0092-7317    

DOI:10.1002/cne.902330410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe nucleus of the lateral olfactory tract (NLOT) was studied in rats with the rapid Golgi method. The nucleus is in the rostral part of the amygdala and has three distinct layers. Layer I is a superficial, fibrous layer; layer II, an intermediate, cell‐dense layer; and layer III, a loosely textured cell and fiber layer. The commissural component of the stria terminalis forms at the apex of layer III. Layer II contains pyramidal and stellate cells; the former is more abundant. The apical dendrites of the pyramidal cells bow outward, point ventrally, and extend through layer I to the pial surface. The apical and basilar dendrites weave a dendrite capsule around layer II, except along its border with layer I. Most pyramidal cell axons go dorsally through layer III into the commissural component of the stria terminalis. The axons normally give off long, thin collaterals that travel rostrally into the forebrain. Other, shorter collaterals remain near the parent cell. Stellate cells have spine‐poor dendrites that radiate throughout layers I and II. Their axons generate a dense terminal field that is confined to layer II. A special group of neurons, the border neurons, occur along the junction between layers I and II. Many of them look like modified pyramidal cells, and some look like horizontal cells. The axons of the latter ramify among the pyramidal cell apical bouquet dendrites in layer I. Along the perimeter of layer I, near the pial surface, are rounded cell bodies that have moderately spiny dendrites and axons that project dorsally. Layer III neurons are the largest cells in the NLOT. Three types of large cells were identified: large spiny neurons, large nonspiny neurons, and pyramidal cells, which were least common. The dendrites of all three neuron types reach beyond layer III into layer II or the adjacent anterior amygdala. Their axons were not followed far. They travel dorsally and give off a few collaterals, some of which enter layer II. Also in layer III, mainly in its apical region, are small nonspiny cells. Their dendrites and axons appear to be limited to layer III. The afferent fibers in layer I generally run parallel to the pial surface. They have a few short collaterals and boutons en passant. One afferent group in layer I is made up of thick axons that enter via the rostral edge of the layer. It looks as though they make repetitive synaptic contacts on pyramidal cell dendrites in layer I. Layer II afferents enter either from the perimeter of the layer or through layer III. The former axons go across the layer, giving off several short collaterals and boutons en passant. The axons that descend into layer II also emit collaterals as they continue ventrally into layer I. A special group of layer II afferent fibers have innumerable varicosities and boutons en passant. Layer III afferents are mostly axons that traverse the layer. They have short collaterals that end in the layer and longer ones that go ventrally through layer II into layer I. We have attempted to correlate our Golgi data about NLOT afferents and efferents with the results obtained by other investigators who have used experimental tract‐tracing methods. We conclude by suggesting that the NLOT may have a significant role in localizing olfactory stimuli to one side of the mi

ISSN:0092-7317    

DOI:10.1002/cne.902330411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY