摘要:

AbstractThe nuclear origin and distribution of midbrain‐olivary fibers has been described in a previous study utilizing axonal transport techniques (Linauts and Martin, '78a). The present report extends their results to the electron microscopic level and details the postsynaptic distribution of such fibers. Lesions within the ventral periaqueductal grey and adjacent tegmentum, the red nucleus or the nucleus subparafascicularis result in electron dense axon terminals within the olive at survival times of 48, 72 and 96 hours. At 72 hours, many degenerating presynaptic profiles shrink, become irregular in shape and are totally or partially surrounded by glial processes. The principal olivary nucleus contains the majority of these profiles. However, the subparafascicular terminals are more abundant in the rostral and intermediate parts of the medial accessory nucleus and the rubral terminals are concentrated within the dorsal lamella of the principal nucleus. The nuclear location of the degenerating terminals was determined by examination of 1 μm plastic sections cut in the transverse plane from each block face prior to thin sectioning. Degenerating terminals were counted in three cases, one from each of the three lesion sites described above. When taken together these cases show that just over 50% of the degnerating terminals are presynaptic to spiny appendages and are located within the synaptic clusters (glomeruli) described previously (King, '76). The percentage of degenerating terminals in the glomeruli increases to 70% when the lesion is in the ventral periaqueductal grey and adjacent tegmentum. The remaining degenerating terminals contact dendritic shafts outside the astrocytic boundaries of the synaptic clusters.The synaptic vesicle populations within the degenerating terminals vary with the location of the lesion. Lesions in the ventral periaqueductal grey and the adjacent tegmentum result in the degeneration of terminals with either clear spherical vesicles or endings with both clear spherical vesicles and a variable number of large dense core vesicles. In contrast, the primary degenerative changes that occur after destruction of the red nucleus or the nucleus sub‐parafascicularis are in terminals with clear spherical vesicles. When the synaptic complex was present in the plane of section, regardless of the site of the lesion, the degenerating terminals could be classified as Gray's type I.Thus, we have demonstrated that afferents from the mesencephalon terminate within synaptic clusters located in the principal and medial accessory (Part A) subnuclei of the inferior olive. Although the mesencephalic afferents have multiple origins (Linauts and Martin, '78a), many of their synaptic terminals contact spiny appendages within the synaptic clusters. This postsynaptic site also receives cerebellar terminals (King et al., '76). The origin of presynaptic profiles within the synaptic clusters that contain clear pleomorphlic vesicles is yet to be determ

ISSN:0092-7317    

DOI:10.1002/cne.901820202

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

年代:1978

数据来源: WILEY

摘要:

AbstractAcetylcholinesterase (AChE) activity has been demonstrated ultra structurally in neurons of the arcuate nucleus and associated with fibers in the arcuate nucleus and the median eminence (ME) of the rat. In addition, the effects of neonatal monosodium glutamate (MSG) treatment and Halász deafferentation on the AChE staining and localization have been studied. Neonatal MSG‐treatment resulted in loss of the majority of AchE‐positive neurons in the arcuate nucleus while leaving neuropil staining intact. Haläsz deafferentation caused a loss of arcuate neuropil activity while leaving the neuronal staining unaltered. These observations are consistent with previous biochemical results suggesting the existence of a cholinergic tuberoinfundibular system with nerve cells in the arcuate nucleus and terminals in the median eminence. In addition, the deafferentation experiments indicated that extra‐hypothalamic cholinergic fibers may innervate the arcuate nucleus. Supporting evidence from other biochemical studies and the curious paucity of histochemical and biochemical AChE activity in the ME are also di

ISSN:0092-7317    

DOI:10.1002/cne.901820203

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

年代:1978

数据来源: WILEY

摘要:

AbstractA high‐affinity uptake mechanism for [3H]‐γ‐aminobutyric acid (GABA) has been localized to type H1 cone horizontal cells and type Abpyriform amacrine cells in the retina of the goldfish by light and electron microscope autoradiography. By stimulating isololated retinas with colored lights during incubation we have been able to use [3H]‐GABA uptake as a probe of light‐evoked changes in membrane potential. All colors of lights increase and darkness decreases [3H]‐GABA uptake by H1 cone horizontal cells. Our model of voltage dependence of GABA uptake predicts that all colors of light should hyperpolarize H1 cone horizontal cells and other investigators have shown by intracellular recording and dye‐marking that type H1 cone horizontal cells hyperpolarize to all wavelengths of light. We have also obtained evidence that dark‐induced depolarizatiion of cone horizontal cells leads to release of GABA. Type Abpyriform amacrine cells show maximal [3H]‐GABA uptake in darkness and when exposed to green or blue lights, but red lights dramatically suppress uptake. We predict these neurons to be red‐depolarizing and recent intracellular recordings and dye‐marking by Famiglietti et al. ('77) support our conclusions. Synaptic relations of apparently GABA‐ergic neurons were investigated in the electron microscope. We propose type H1 cone horizontal cells to be both pre‐ and post‐synaptic to red‐sensitive cones and type Abpyriform amacrine cells to be both pre‐ and post‐synaptic to red‐sensiti

ISSN:0092-7317    

DOI:10.1002/cne.901820204

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe hippocampus of the fence lizard (Sceloporus undulatus) is composed of two laminated regions that are readily distinguishable on the basis of position and perikaryal size in Nissl preparations: the small‐celled (Hsc) and the large‐celled (Hlc) hippocampal divisions. Based upon cellular and fibrillar characteristics, the layers of the Hsc are: (1) the superficial plexiform layer; (2) the cellular layer; (3) the deep plexiform layer; (4) the layer of deep fibers, or alveus; and, (5) the ventricular ependyma. The layers of the Hlc are: (1) the tangential layer; (2) the molecular layer; (3) the pyramidal layer; (4) the deep plexiform layer; (5) the alveus; and, (6) the ventricular ependyma. The neurons of each hippocampal layer were grouped into classes based upon somal position and appearance, and dendritic and axonal arborization patterns in Golgi sections. Neurons of the Hsc are more numerous and pleomorphic than those of the Hlc. Data do not suggest an intrinsic organization that closely parallels that found in the mammalian hippocam

ISSN:0092-7317    

DOI:10.1002/cne.901820205

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe development of the lateral geniculate nucleus has been studied systematically in Nissl preparations from a series of cats that ranged in age from newborn to adult. In addition, preliminary observations are reported at two stages of fetal development.It was found that laminae develop in the lateral geniculate nucleus near the time of birth and continue to differentiate during the first postnatal week. During development the major axis of the lateral geniculate rotates approximately 180° in the sagittal plane. The rotation begins prenatally and is not completed until after the twentieth postnatal week.The volume of the lateral geniculate was computed at different ages and it was determined that during the first postnatal month the nucleus attains two‐thirds of its adult size. However, the rate of growth declines markedly thereafter, and final volume, like final position, is not achieved until late in development.The cross‐sectional areas of lateral geniculate neurons were measured at four locations in the nucleus in each animal. The locations represented the following parts of the visual field: the paracentral and inferior peripheral fields in the binocular segment of lamina A; the monocular segment of lamina A; and the paracentral field in lamina A1. Neurons in each of these locations grow at approximately the same rate and are essentially fully grown by 56 days. Cell size histograms show that more large cells are found in lamina A1 and more small cells in the monocular segment than elsewhere in the dorsal laminae. Unlike the retina, there appears not to be a gradient of development in the lateral geniculate nucleus from center to periphery, at least in terms of cell body size at the ages studied. On the contrary, that part of the lateral geniculate nucleus which represents the paracentral visual field is the last segment in the dorsal laminae to achieve a mature cell size distribution.Finally, a discrete class of small spindle‐shaped neurons was observed in the lateral geniculate nucleus ventral and caudal to the C laminae during the first two postnatal weeks. These cells possess a leading and trailing cytoplasmic process and are distinctly different from cells in the main laminae. It is suggested that these spindle‐shaped cells may be neurons that are still in the process of migration or differentiation in the postnata

ISSN:0092-7317    

DOI:10.1002/cne.901820206

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe olivocerebellar projection to lobulus simplex, crus I and II in the cat was investigated by means of retrograde axonal transport of horseradish peroxidase (HRP). The distribution of labeled cells in the inferior olive following HRP injections in lobulus simplex, crus I and II confirmed the findings by Brodal ('40b) that the rostral half of the principal olive projects to these areas of the cerebellar hemisphere. However, concerning details there are some differences in so far as the heaviest contribution to crus I comes from the medial parts of the ventral and dorsal lamella, that to crus II from its lateral part, especially the ventral bend. The present findings show that in addition the rostral part of the medial and the rostramedial part of the dorsal accessory olive project to these areas of the cerebellar corotex. Further details in the projection are shown in figure 8B. The findings agree fairly well with the electrophysiological results of Armstrong et al. ('74) and the experimental anatomical data of Groenewegen and Voogd ('77a, b). An attempt is made to correlate the findings with the pattern of longitudinal zonal subdivision of the cerebellum. There is evidence for a topical organization within the projection to crus I and II and parts of their projection areas in the principal olive.The distribution of the labeled cells which project to lobulus simplex, crus I and II is discussed in relation to afferent pathways to the inferior olive.

ISSN:0092-7317    

DOI:10.1002/cne.901820207

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe feline RN contains neurons which fall into three size categories: giant (40–80 μm), medium (25–35 μm) and small (6–20 μm). These three populations of rubral neurons are distinguishable on the basis of a number of ultrastructural criteria and form classes not dissimilar from the traditional three divisions of cell types. Each of the three populations of rubral neurons can be further divided into three subgroups on the basis of a large number of configurational criteria discernible by the Golgi‐Cox method. Each of these nine cell types are clearly separate, distinguishable by at least three criteria, and are found in different regions of the RN.It is shown that in 5‐day prenatal kitten, rubral neurons are already organized into the aforementioned three size categories. At this age most of the subpopulations are also distinguishable by the Golgi‐Cox method. However, the giant rubral neurons (about 30 μm) and the medium sized cells (about 20 μm) are much smaller than in the adult cat. The dendrites elaborate many fine processes which emerge from multiple varicosities. The neuropil differs strikingly from that of the adult in that the vast majority of axons are small and unmyelinated.A number of changes in the RN are apparent as the kitten matures. The larger rubral cells undergo configurational changes before the smaller neurons, yet the giant cells continue to grow for a longer period of time. In the perinatal period, the extent of arborization of the dendritic trees diminishes, the number of spines decreases, and the long dendritic spines shorten. Somatic spines first appear in the giant cells at about one week after birth. In prenatal kittens, large cells frequently elaborate a tuft of fine branching processes in one region of the soma. These tufts later diminish in size and disappear by one week post‐natal.Recent investigations (Pompeianao, '59; Condé, '66; King et al., '73; Sadun, '75) indicates that the RN of the cat is highly organized and very heterogenous. Afferent terminals are restricted to certain regions of certain cell types which are themselves specifically located within the RN. This specificity is apparent in perinatal kittens, despite the manifest immature a

ISSN:0092-7317    

DOI:10.1002/cne.901820208

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

年代:1978

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901820201

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

年代:1978

数据来源: WILEY