摘要:

AbstractThe electron microscopic (EM) autoradiographic method has been used to determine the size, distribution, and ultrastructure of retinocollicular axon terminals following intraocular injection of either (3H)‐leucine or (3H)‐proline.In the contralateral colliculus, retinal terminals are most numerous in the uppermost sublamina of the superficial grey, SGS1. The mean diameter of terminals in the contralateral SGS1 and SGS2 is 1.3 μm ± 0.33, and 1.45 μm ± 0.37, respectively. The mean diameter of terminals in the deepest contralateral sublamina, SGS3 (1.85 μm ± 0.62), is significantly larger than the mean diameter of those in the contralateral SGS1 or SGS2.By contrast, the mean diameter of terminals in different sublayers of the ipsilateral superficial grey is relatively constant, ranging from 1.56 μm ± 0.45 to 1.63 μm ± 0.60. Most ipsilateral retinal terminals are located in the uppermost part of SGS2.It is postulated that there are two populations of retinal terminals in the superficial grey: a population of smaller terminals present in the contralateral SGS1 and SGS2, and a population of larger terminals present in the contralateral SGS3. Both populations appear to be present in the ipsilateral sublaminae.While all labeled retinocollicular terminals contain round vesicles and asymmetric membrane thickenings, two morphological features appear to be correlated with retinal terminal size: (1) the population of smaller retinal terminals more frequently contacts postsynaptic profiles containing scattered round vesicles; and (2) large, dense‐core vesicles are more commonly associated with the presynaptic profiles of the population of larger terminals.A comparison of these morphological findings with available physiological data (Hoffman, 1973; Fukuda and Stone, 1974; McIlwain and Lufkin, 1976 McIlwain, 1978) suggests that the smaller terminals may be those of W‐retinal ganglion cells, and the larger terminals those of Y‐ret

ISSN:0092-7317    

DOI:10.1002/cne.901990102

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

年代:1981

数据来源: WILEY

摘要:

AbstractPrevious workers have reported a five fold decrease in motoneuron numbers occurring from birth to adulthood in the rat. It has also been reported that forelimb muscles receive connections from motoneurons in both ventral horns prior to day 14 of life in the rat and that the contralateral cells subsequently degenerate completely by day 21. In the present study, postnatal changes in motoneuron number and distribution within the ventral horn were studied in the rat using the technique of retrograde horseradish peroxidase (HRP) transport following intramuscular infusion of HRP into biceps brachii (BB). Peripheral nerves other than those to BB were sectioned and ligated to control for HRP diffusion. The spatial organization of BB motoneurons was compared in animals 9‐14 days old and adult animals using computer 3‐D reconstruction. This allowed observations of the BB motoneurons from a variety of perspectives in relationship to a number of spinal cord landmarks and avoided the necessity for transverse and horizontal sectioning of the cords in alternate animals. A decrease of 50‐75% in the number of HRP filled motoneurons number was found from birth to adulthood (adults 98‐150, neonates 172‐243). The spatial arrangement of the BB motoneurons with regard to the root entry zones and other landmarks such as the dorsolateral convexity of the ventral horn, remains constant from birth to adulthood. No evidence was found to support the existence of inappropriate connections from motoneurons in either the ipsi or contralateral ventral horns of neonate rats. It is suggested that the comparatively small decrease in motoneurons postnatally could be a continuation of the histogenetic processes of cell death begun in utero and is related to the postnatal development of the central and peripheral connections of mo

ISSN:0092-7317    

DOI:10.1002/cne.901990103

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe somatotopic pattern of the connections of the ventroposterior nucleus of the thalamus with the representations of the body surface in somatic cortical Areas 3b and 1 were investigated in macaque monkeys using the anatomical tracers horseradish peroxidase (HRP), and3H‐proline. These tracers, in combination or separately, were injected into one or more cortical sites, after the skin surface capable of activating neurons at each site had been defined with microelectrode mapping methods. These injection sites were later related to the overall organizations of the two cutaneous representations as determined in more extensive mapping experiments (Nelson et al., 1980). Finally, zones of anterograde and retrograde label in the thalamus were located with reference to architectonically defined subnuclei in the ventroposterior nucleus (VP). The results led to the following conclusions. (1) Zones of cells in VP projecting to a given location in either Area 3b or 1 also receive reciprocal projections from the cortical target. (2) A given cortical location typically relates to a disc‐shaped or lamellar region in VP with the disc extending rostrocaudally and dorsoventrally, being most narrow in the mediolateral dimension. (3) The representations of the same body surface in Area 1 and Area 3b relate to the same region of VP. However, since fewer cells were generally labeled after Area 1 injections, less dense terminations are suggested from VP to Area 1 than to Area 3b. (4) VP is the major or exclusive relay of somatosensory information to the two cutaneous representations from the thalamus. Labeled neurons or zones of terminations were found outside VP in other parts of the somatosensory thalamus only when injection sites extended into cortex outside Areas 3b and 1. (5) The face, hand, limbs, and foot are represented in a mediolateral sequence of subnuclei within VP. A dorsal capping subnucleus is apparently largely devoted to the axial trunk and perhaps other hairy skin surfaces such as some parts of the proximal surfaces of the limbs. (6) While anterior and posterior surfaces of the hind limb are widely separated by the glabrous foot in the cortical representations, they appear to be represented in adjacent zones in the thala

ISSN:0092-7317    

DOI:10.1002/cne.901990104

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe organization of the olivocerebellar projection to the pyramis and copula pyramidis in the rat has been studied with the use of microinjections of horseradish peroxidase (HRP). These injections were made in different mediolateral positions along the width of this lobule. The objective was to determine the subnuclear origin of parasagittal zones of olivary innervation. The results indicate that six zones of varying width can be distinguished, each of which receives a different olivary projection. Injections in the pyramis in succedingly more lateral positions resulted in retrograde labeling of the lateral part of the caudal medial accessory olive (MAO), nucleus ß of the MAO, and a slightly more rostral part of the lateral MAO. Injections in the copula pyramidis result in retrograde labeling of the lateral part of the dorsal accessory olive (DAO), the intermediate part of the MAO, and the caudal tip of the principal olive. In very few of the experiments was there labeling of more than one subnuclear locus within the inferior olivary complex. These results suggest that parasagittal zones within the pyramis and copula pyramidis of the rat cerebellum receive highly ordered and differential projections from the inferior olivary complex

ISSN:0092-7317    

DOI:10.1002/cne.901990105

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

年代:1981

数据来源: WILEY

摘要:

AbstractIn this study, using the horseradish peroxidase (HRP) retrograde tracing technique, the pontocerebellar projection to the pyramis and copula pyramidis in the rat has been analyzed in a series of experiments which had been performed to study the olivocerebellar projection (Eisenman, '81). Microinjections of HRP were made in different mediolateral positions along the width of the pyramis and copula pyramidis. Injections situated within the pyramis but in different loci resulted in the retrograde labeling of primarily two bilateral (much heavier contralaterally) groups of pontine cells: a medial and a ventrolateral group, both situated in the caudal pontine nuclei. With injections in the intermediate region, i.e., the border between the pyramis and copula pyramidis, a different pattern of labeled cells is seen. In these cases the intermediate part of the caudal pontine nuclei contains labeled cells. Injections placed in the lateral parts of the copula pyramidis resulted in still another pattern of retrograde labeling. Injections in this region resulted in the presence of labeled cells in four pontine areas, three caudal groups, and one group in the rostral pontine nuclei. Two of the caudal groups overlap with, but extend more rostrally than, the regions containing labeled cells after pyramis injections. These data suggest the presence in the pyramis and copula pyramidis of three parasagittal zones of differing widths, each of which receives a mainly differential projection from the pontine nuclei.

ISSN:0092-7317    

DOI:10.1002/cne.901990106

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

年代:1981

数据来源: WILEY

摘要:

AbstractOptic nerve regeneration was examined with [3H]proline radioautography in fish that had one nerve crushed. Fibers had not yet grown beyond the crush site at 2 days post‐crush (PC) and were at the optic chiasm by 4–5 days PC. By 6 days PC the fibers had reinnervated the rostral pole of the contralateral tectum, the lateral geniculate nucleus and area pretectalis dorsalis and ventralis. Area preopticus, nucleus opticus dorsolateralis and nucleus opticus commissurae posterior were partially reinnervated by 8 days PC. At this time numerous abnormal targets were labeled, including nucleus rotundus, nucleus isthmi, cerebellum, pituitary gland and ipsilateral optic tectum. Optic fibers also entered the posterior, intertectal and horizontal commissures, as well as tractus rotundus, the tectocerebellar, tectobulbar and mesencephalocerebellar tracts. In addition, fibers within the contralateral optic tectum were not restricted to their usual laminae. They were distributed from the superficial edge of the tectum to the ventricle. At 32 days PC only the normal retinal projections were evident, and all of the anomalous projections had disappeared. The anomalous projections may have either retracted or degenerated or become undetectable with radioautogra

ISSN:0092-7317    

DOI:10.1002/cne.901990107

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

年代:1981

数据来源: WILEY

摘要:

AbstractRetinofugal pathways in the painted turtle were examined with autoradiographic and HRP methods. The majority of the retinal fibers decussate at the optic chiasm and course caudally to terminate in 12 regions of the diencephalon and mesencephalon. The pars dorsalis of the lateral geniculate nucleus is the densest target in the thalamus. Two nuclei dorsal to pars dorsalis—the dorsal optic and dorsal central nuclei—receive optic input. Three nuclei ventral to pars dorsalis are retinal targets—the ventral geniculate nucleus, nucleus ventrolateralis pars dorsalis, and nucleus ventrolateralis pars ventralis. Contralateral fibers course through the pretectum where they terminate in nucleus geniculatis pretectalis, nucleus lentiformis mesencephali, nucleus posterodorsalis, and the external pretectal nucleus. Retinal fibers also terminate within the superficial zone of the optic tectum. HRP material demonstrates three optic fiber layers—laminae 9, 12, and 14. Optic fibers leave the main optic tract as a distinct accessory tegmental optic pathway and terminate in the basal optic nucleus. Ipsilateral retinal terminals occur in a pars dorsalis and a pars ventralis of the lateral geniculate nucleus, the dorsal optic nucleus, nucleus posterodorsalis, the basal optic nucleus, and in laminae 9 and 12 of the optic tectum. Rostrally, the ipsilateral tectal fibers occupy two zones along the medial and lateral tectal roof; these zones converge caudally and are continuous along the caudal wall of the

ISSN:0092-7317    

DOI:10.1002/cne.901990108

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe distribution of substance P‐containing fibers within the hippocampal formation of the cat was examined using an immunohistochemical approach. A new, indirect immunoperoxidase method based on the high affinity binding of vitamin H (biotin) by avidin was developed to demonstrate substance P‐like immunoreactive fibers. The neocortex contained only occasional single substance P fibers. In contrast, the archicortical structures contained a well organized substance P innervation. The entorhinal area of the parahippocampal gyrus contained a delicate network of varicose axons which appeared to ascend form the subcortical white matter to terminate predominantly in layer II. The subiculum contained a network of positive varicosities throughout the neuropil of both the pyramidal and the molecular layers. These substance P terminals appeared to arise, at least in part, from fibers entering laterally across the angular bundle. Within the ventral hippocampus the substance P innervation was predominantly in the pyramidal cell layer, and was heaviest in field CA3 and weakest in CA1. Some fibers were also observed in strata oriens, lucidum, and radiatum. Occasional varicose fibers could be seen entering the hippocampus from the fimbria. Within the dentate gyrus the substance P fibers were most concentrated in the supragranular layer and among the more superficial of the granule cells. A moderately dense plexus of fibers also occurred in the neuropil of the hilus among the polymorphic cells. In addition, a distinct, narrow band of varicosities was found at the outer edge of the inner molecular layer, while the outer molecular layer did not contain any positive elements.It is concluded that the hippocampal formation receives a distinct, well organized substance P innervation. Substance P fibers appear to enter the hippocampus both laterally across the angular bundle and ventrally through the fimbria. From this detailed examination of the distribution of the substance P fibers within the hippocampus in relation to the other known inputs to this area it is suggested that many of the substance P fibers arise in or, more probably, pass through the septal area to innervate the hippocam

ISSN:0092-7317    

DOI:10.1002/cne.901990109

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

年代:1981

数据来源: WILEY

摘要:

AbstractCessation of cell proliferation and cell death were studied in the dorsal motor nucleus of the vagus of the chick embryo, hatchling, and adult. Most of the cells comprising the nucleus (94%) complete their final DNA synthesis on days 2 and 3 of incubation. There is a caudo‐rostral gradient in the cessation of proliferation, with the caudalmost cells withdrawing from the cell cycle slightly in advance of the middle and rostral cells. Cell death in the dorsal motor nucleus results in a 21% loss of cells between days 8 and 12, and 37% loss by hatching. A caudo‐rostral gradient was also present with respect to cell death, with more delayed and gradual cell loss occurring in the rostral region. The timing and spatial pattern of cell death may be related to the asynchronous innervation of the several targets of the nucl

ISSN:0092-7317    

DOI:10.1002/cne.901990110

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe time of neuron origin in the trigeminal ganglion was examined in autoradiograms of 60‐day‐old rats that were exposed to a single pulse of3H‐thymidine on day 11, 12, 13, 14, or 15 of gestation. Heavily labeled neurons, representing cells in or near their last mitotic division at the time of the pulse label, were present in animals injected between embryonic days 11 and 13 with a peak on day 12. Within this time period, larger neurons were generated prior to smaller neurons with a peak for larger cells on day 12 and for smaller cells on day 13. Thus, the majority of trigeminal ganglion neurons are generated over a three‐day period just after the midpoint of gestation.Neuron number, size, type, and cytoarchitectural organization were also examined in the ganglion. The mean neuron count per ganglion was 52,372. The size distribution of these cells ranged continuously from 7–61 μm (mean diameter) with no evidence for clearly defined subpopulations. The staining intensity and distribution patterns of the Nissl substance varied greatly from cell to cell precluding the classification of cells as light or dark. Little correspondence between these Nissl features and cell size was found. Among the clusters and rows of neurons in the ganglion, we did not see consistent cytoarchitectonic patterns which might reflect specific sensory recept

ISSN:0092-7317    

DOI:10.1002/cne.901990111

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

年代:1981

数据来源: WILEY