摘要:

AbstractThis study presents evidence that the X‐ and Y‐ cells described physiologically in the A laminae of the cat's dorsal lateral geniculate nucleus (LGN) are two morphologically distinct cell types recognizable in Golgi preparations.It is shown firstly that the three cell types seen in Golgi preparations of the A laminae (large and medium‐sized principal cells and small interneurons–types 1,2 and 3 in the classification of Guillery, 1966) may be identified in 1‐μm Epon sections of osmicated material. While cell‐diameter histograms prepared from serial 1‐μm sections show a unimodal distribution of cell sizes, three populations can be distinguished if attention is paid to the presence or absence of large cytoplasmic inclusions (laminar bodies). These three populations consist of large cells lacking laminar bodies (Class I), medium‐sized cells possessing laminar bodies (Class II) and small cells lacking them (Class III). That these three classes correspond to the three morphological types has been shown by (i) size comparisons, and (ii) direct demonstration of laminar bodies in the Golgi‐impregnated cell bodies of Guillery's type 2 cells.Histograms prepared in this way for samples taken at various positions in the LGN show that the numbers of class II cells decline from the representation of the area centralis to the monocular segment. This decline is compensated by a corresponding rise in the numbers of class I cells. This pattern of distribution is similar to the physiologically observed distribution of X‐ and Y‐cells, indicating that X‐cells are likely to be class II cells and Y‐cells class I cells.The cortical projections of the various cell types have been examined by the horseradish peroxidase method. Class II cells project to area 17 only. Most class I cells also project to area 17 only, but a few very large class I cells project to area 18. From our results,;it appears that very few if any cells in the A laminae have branching axons supplying both 17 and 18. The class III cells do not project to the visual cortex, a finding consistent with their identification as interneurons.Class I and II cells are also found in lamina C and in the MIN. In both these regions there is a predominance of very large class I cells, which project to area 18. Laminae C1‐C3 contain small cells lacking laminar bodies. These cells may project to both areas 17 and 18 with branching axons. They are likely to correspond to Guillery's type 4 cells (small relay cells confined to the C laminae) and to the physsiologically described W‐cells.Long‐term monocular deprivation causes cells shrinkage which is much more severe for class I than for class IIcells. There is in addition a decrease in the relative numbers of class I cells. This decrease is found in binocular deprivation also. These observations provide an anatomical basis for the reported loss of Y‐cells from deprived laminae of the LGN. It is suggested that the effects of deprivation on Y‐cells may be accounted for in te

ISSN:0092-7317    

DOI:10.1002/cne.901720402

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

年代:1977

数据来源: WILEY

摘要:

AbstractThree variants of the Golgi method were employed to examine the cell types, their dendritic fields and organization and azonal trajectories within the substantia nigra of albino and hooded rats. In both sagittal and coronal sections, large, medium and small neurons were classified on the basis of soma size, extent of dendritic fields and dendritic caliber. In general nigral cells have three to five primary dendrites that branch relatively infrequently. Some dendrites of all cell types have thinly scattered spines or varicosities.Small cells, found in all areas of the nucleus, have thin dendrites and small, nondirectional dendritic fields. These are considered to be interneurons. The medium cells found in pars compacta, presumed to be the dopaminergic cells of the nigroneostriatal pathway, send long dendrites into pars reticulata perpendicular to the course of pars compacta. In addition, these cells have a number of dendrites which remain in pars compacta. These cells have axons that run medio‐dorsaslly. No axon collaterals were detected. Both large and medium cells are found in pars reticulata. Cells in the dorso‐medial aspect of pars reticulata orient rostro‐caudally and roughly perpendicular to the course of pars compacta, while cells in the perpeduncular area show a strict orientation which is parallel to the crus cerebri. Some pars reticulata cells emit axon collaterals while others remain unbranched for their observable length. Both large and medium cells are also seen in pars lateralis. These cells send long dendrites ventrally into pars reticulata where they run parellel to the crus cerebri, while some shorter dendrites remain in pars lateralis.In total, the substantia nigra appears to have a layered organization: the superior layer is the cellular pars compacta, the second is the dorso‐medial area of pars reticulata where both pars compacta and pars reticulata dendrites run rostro‐caudally and dorso‐ventrally and the third layer is the perpenduncular region where dendrites from all areas run parallel to the c

ISSN:0092-7317    

DOI:10.1002/cne.901720403

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

年代:1977

数据来源: WILEY

摘要:

AbstractTo study the central connections of ventral root afferents, horseradish peroxidase was injected into the lumbosacral spinal cord of the cat and the appropriate dorsal ganglia were examined from segments with (1) both dorsal and ventral roots intact, (2) both roots sectioned, and (3) only the dorsal root sectioned. The key finding was that a number of labeled cells (up to 133) were observed in the ganglion after dorsal rhizotomy. We interpret these findings to mean that the central processes of the labeled cells projected to the spinal cord through the ventral root. As expected, when both roots wer cut, almost no cells were labeled and when both roots were intact, there were large numbers of labeled cells.Of the labeled cells observed in ganglia after dorsal rhizotomy, all were found to be within the ganglion itself. No labeled aberrant dorsal root ganglion cells could be found.

ISSN:0092-7317    

DOI:10.1002/cne.901720404

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe gross morphology of the tongue of the Mongolian gerbil (Meriones unguicultatus), the location of papillae and taste buds, and the normal innervation pattern of the tongue asnd taste buds were determined. The chorda tympani nerve was interrupted to produce degeneration of fungiform taste buds. Regenerating chorda tympani axons followed the original nerve pathways in the tongue en route to the furniform papillae in the epithelium where they initiated the regeneration of taste buds. The spastial distribution of reinnervated fungiform papillae and reformed taste buds was examined 7 to 19 days following surgery. Beginning at eight days following chorda tympani interruption there was a progressive increase, first, in the proportion of fungiform papillae that were reinnervated, and later in the number of reformed taste buds. On the basis of these measures it was concluded that a taste bud is reformed one to two days after reinnervation of its papilla. From the time course of reinnervation of the fungiform papillae it was calculated thast some fibers regenerated at rates in excess of 2mm/day. Regeneration was precise and systematic. The regenerating chorda tympani fibers accurately returned to the fungiform papillae; they did not follow the pasthways of lingual nerve axons. In the initial stages of recovery both reinnervated papillae and reformed taste buds weere preferentially located toward the front of the tongue; the reinnervation of posterior fungiform papillae was delayed.

ISSN:0092-7317    

DOI:10.1002/cne.901720405

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

年代:1977

数据来源: WILEY

摘要:

AbstractCrushing or transecting the chorda tympani nerve of the gerbil (Meriones unguiculatus) caused ipsilateral degeneration of taste buds in the fungiform papillae. In less than two weeks some taste fibers regenerated into the tongue and formed new taste buds and receptor cells. The recovery process was evaluated electrophysiologically in 53 gerbils by acute recording proximal to the nerve injury site. Initially the chorda tympani was electrically silent. In gerbils tested at later times spontaneous activity appeared. This was followed by responses to pressure on the tongue. Taste responses returned as early as dasy 11. The receptive field of regenerated taste fibers was limited to a small number of fungiform papillae. Taste responses were always associasted with the presence of one or more taste buds in the receptive field. Taste buds identified as responsive to chemicals contained some fusiform cells.We found thast the taste responses of single fiber, few‐fiber and multi‐unit preparations reflected the diversity of responses found in normal taste axons as determined by recording from 26 normal single fibers and 27 normal whole nerves. The early emergence of a variety of fiber types and responses to many chemicals in regeneration is inconsistent with the proposition that the relative chemical responsiveness of a receptor cell is strictly a function of its age; the response of a given young taste receptor is not necessarily limited to a few of the standard taste stimula

ISSN:0092-7317    

DOI:10.1002/cne.901720406

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

年代:1977

数据来源: WILEY

摘要:

AbstractTimes of final mitotic division for neurons of the epithalamic, dorsasl thalamic and subthalamic nuclei of the rat were determined with the aid of thymidine‐H3autoradiography. Intensely labelled neurons were observed in the brains of animals injected with radiochemical from days 13 to 19 of gestation. The pattern of distribution of the labelled neurons indicated that neurogenesis in these regions followed caudorostral, lateromedial and ventrodorsal neurogenetic gradients, all of which were found to operate simultaneously. Since neurogenesis in the epithalamus, subthalamus and caudolateral thalamic regions began on days 13 and 14 of gestation, the ventrodorsal and lateromedial proliferative gradients were clearly discerned only within the ventral and dorsal thalamus exclusive of the epithalamus. These directional neurogenetic gradients were apparent throughout the entire thalamus and within individual thalamic nuclei. No neurogenetic pattern based upon neuronal size was observed, i.e., large neurons were not preferentially formed earlier than smaller ones. Detailed information has also been provided on the cytological character of each thalamic nucleu

ISSN:0092-7317    

DOI:10.1002/cne.901720407

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

年代:1977

数据来源: WILEY

摘要:

AbstractProjections asre described from the basolateral, lateral and anterior cortical nuclei of the amygdaloid complex, and from the prepiriform cortex, to several discrete areas of the cerebral cortex in the rat and cat and to th mediodorsasl thalamic nucleus in the rat. These projections are very well‐defined in their origin, and in their area and laminar pattern of termination.The basolateral amygdaloid nucleus can be divided into anterior and posterior divisions, based on cytoarchitectonic and connectional distinctions. In both the rat and cat the posterior division projects to the prelimbic area (area32) and the infralimbic area (area 25) on the medial surface of the hemisphere. The anterior division projects more lightly to these areas, but also sends fibers to the dorsal and posterior agrangular insular areas and the perirhinal area on the lateral surface. Furtheremore, in the cat the perirhinal area is divided into two areas(area 35 and 36) and the anterior division projects to both of these and also to a ventral part of the grangular insular area; this last area is adjacent to, but separate from the auditory insular area and the second cortical taste area. In most of these areas, the fibers from the basolateral nucleus terminate predominantly in two bands: one in the deep part of layer I and layer II, and a heavier band in layer V (in the rat) or layers V and VI (in the cat).The lateral amygdaloid nucleus projects heavily to the perirhinal area, and also to the posterior agranular insular area. These fibers terminate predominantly in the midle layers of the cortex, although the cellular lamination in these two areas is relatively indistinct. The anterior cortical amygdaloid nucleus and the prepiriform cortex both project to th infralimbic area and the ventral agranular insular area, and the anterior cortical nucleus also projects to the posterior agranular area and the perirhinal area. In all of these areas, the fibers from these olfactory‐relasted structures terminate in the middle of layer I.In the rat, the two divisions of the basolateral nucleus also project to the medial segment of the mediodorsasl thalamic nucleus, with the anterior division projecting mainly to the posterior part of this segment and the posterior division to the anterior part. The endopiriform nucleus, deep to the prepiriform cortex, projects to the central segment of the mediodorsasl nucleus, since little or no projection could be demonstrated from the prepiriform cortex itself. Projections to the mediodorsal nucleus have not been found in the

ISSN:0092-7317    

DOI:10.1002/cne.901720408

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

年代:1977

数据来源: WILEY

摘要:

AbstractAxonal projections are described from the lateral and hasolateral nuclei of the amygdaloid complex, and from the overlying periamygdaloid and pre‐piriform cortices and the endopiriform nucleus, to the lateral entorhinal area, the ventral part of the subiculum, and the parasubiculum in the cat and rat. All of these projections have well‐defined laminar patterns of termination, which are complementary to those of other projections to the same structure.Based on these results, and on cytoarchitectonic distinctions, the lateral entorhinal area has been divided into dorsal, ventral, and ventromedial subdivisions. The olfactory bulb and prepiriform cortex project to layers IA and IB, respectively, of all three subdivisions, but the lateral amygdaloid nucleus has a restricted projection to layer 111 of the ventral subdivision only. The periamygdaloid cortex projects to layer II of the ventromedial and adjoining parts of the ventral subdivisions.The ventral part of the subiculum receives fibers from the posterior division of the hasolateral nucleus, which terminate in the cellular layer and the deep half to one‐third of the plexiform layer. The periamygdaloid cortex and the endopiriform nucleus also project to the same part of the subiculum, but these fibers terminate in the outer part of the plexiform layer. None of these projections extend into the dorsal part of the subiculum.The posterior division of the basolateral nucleus also projects to the posterodorsal part of the parasubiculum (“parasubiculum a” of Blackstad, 1956). These fibers end in the deeper part of the plexiform layer and the superficial part of the cellu

ISSN:0092-7317    

DOI:10.1002/cne.901720409

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

年代:1977

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901720401

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

年代:1977

数据来源: WILEY