摘要:

AbstractThe Purkinje cell degeneration(pcd)mutant mouse rapidly loses cerebellar Purkinje cells between 3 and 5 weeks after birth and slowly loses retinal photoreceptor cells during the first year of life. In the present study, the retinal degeneration in thepcdmouse was analyzed by light microscopy and autoradiography throughout the first 15 months of age. By day 25 there is an abundance of pyknotic photoreceptor nuclei and many outer segments are clearly disorganized. Thereafter, as the photoreceptor cells are lost, their outer segments slowly become shorter and more variable in length; this slow change in length is explained by an almost proportional reduction in both rod outer segment renewal and disc shedding rates. At about 2 months of age, the rate of rod outer segment renewal is slightly less than half that in littermate controls, and the number of large phagosomes in pigment epithelial cells during the burst of disc shedding soon after light onset is one‐half or less than that seen in littermate controls. Between 2 and 10.5 months of age, the retina in the inferior hemisphere of the eye shows substantially more‐advanced photoreceptor degeneration than does the superior hemisphere, particularly in the far peripheral retina. A central‐toperipheral gradient of degeneration is conspicuous in the superior hemisphere; a similar but less obvious gradient of degeneration is also seen in the inferior hemisphere of the eye. Loss of photoreceptor cells and their synaptic terminals results in a predictable thinning of the outer synaptic layer. However, the inner nuclear layer shows no measurable thinning and the inner synaptic layer is reduced in thickness by only about 5–15%. Beginning at about 10 months of age, foci of thinned pigment epithelial cells are evident, and by 12 months there is some vascularization of the pigment epithelium by retinal capi

ISSN:0092-7317    

DOI:10.1002/cne.902120302

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe cerebellar ataxia in Purkinje cell degenerationpcdmutant mice results from the rapid loss of Purkinje cells between 3 and 5 weeks after birth. The loss of photoreceptors in these mutants begins about the same time but proceeds slowly, with most photoreceptors being lost by 1 year of age. In this study the retinas ofpcd/pcdmice and their littermate controls from the age of 10 postnatal days to 15 months were analyzed by electron microscopy. The first signs of photoreceptor cell degeneration are apparent in the region of photoreceptor inner segments as early as postnatal day 13, and more prominently at day 18. During this time, the degeneration is characterized by a large number of vesicles, ranging in diameter from 150 to 350 nm, which are located in the extracellular space adjacent to the photoreceptor inner segments. Analysis of serial sections shows that most of these membrane‐bound degeneration profiles are tubular in shape and some are continuous with the cell membrane of the inner segment. There‐lore, these [profiles] are thought to arise from tubular outpocketings of the inner segments which cleave off to form isolated membrane‐bound profiles. This represents a new and unusual form of photoreceptor degeneration. While the most obvious abnormality in the retina is degeneration of photoreceptor cells, Müller cells also appear to be affected, with swollen apical processes often seen coursing through the outer nuclear

ISSN:0092-7317    

DOI:10.1002/cne.902120303

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractPieces of cerebellar primordia from (days 14 or 15 of gestation) E14 or E15 rat embryos were dissected out and transplanted into a cavity of the occipital cortex and underlying hippocampus, over the superior colliculus of 2‐month‐old rats. The host animals were allowed to survive for 2 to 3 months. The cytoarchitectonic and the synaptic organizations were analyzed in 16 of such transplants. Only 4 of the implants established connections with the host brain through several thin peduncles composed of myelinated fibers. The remaining 12 implants survived in an extraparenchymal situation. Independently of its partial linking to the host brain, the graft grew and developed a cerebellar structure composed of nuclear and cortical regions. The latter exhibited normal lamination and foliation, and contained the five categories of neurons which characterize normal cerebellar cortex.Electron microscopic examination disclosed that the synaptic connections normally present in the cerebellar cortex were also formed in the implants with the exception of climbing fibers, which were absent. The cerebellar interneurons kept their normal topographic distribution and gave origin to numerous synapses which maintained their own specificity. Some mossy fibers were present in the granule cell layer at the center of typical glomeruli. However, abnormal synaptic arrangements were also observed within the neuropil of this granule cell layer. They consisted of pseudo‐glomerular formations composed of clusters of tightly packed small axon terminals covered by granule cell dendrites. The origin of these boutons was not established. Since they did not correspond to the classes of presynaptic elements normally synapsing on these dendrites, they constitute a new example of cerebellar heterologous synapses. Their presence could be related to changes in the cellular environment due to the rarity of mossy afferents.HRP tracing experiments, carried out in extraparenchymal transplants, have allowed us to determine that the corticonucleocortical loop of normal cerebellum is also developed in the implants. Nuclear neurons are at the origin of the mossy fibers involved in glomerular formations, whereas Purkinje cells project to the nuclear region. The establishment of these reciprocal connections could determine the functional stabilization of both kinds of cerebellar neurons and thus the long survival of extraparenchymal grafts.These results allow the conclusion that the presence of extracerebellar afferents is not necessary for the organotypic and synaptotypic differentiation of cerebellar a

ISSN:0092-7317    

DOI:10.1002/cne.902120304

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe majority of substance P‐like immunoreactive (SPLI) fibers in the lateral septal area (LS) are supplied by SPLI cells in the area (BAL between the anterior hypothalamic nucleus and the lateral hypothalamus, and by those in the nucleus latero‐dorsalis tegmenti (TLD)). These conclusions are based on following: (1) Unilateral destruction of the BAL resulted in an ipsilateral decrease in the septal SPLI fibers similar to that seen after the destruction of the TLD, and (2) simultaneous destruction of the BAL and TLD caused a marked reduction of SPLI fibers in the LS on the operated side. The possibility that the destruction of the BAL affected the ascending SPLI system from the TLD seems to be excluded, because (1) the destruction of the TLD resulted in a decrease in SPLI fibers in the ipsilateral medial forebrain bundle (MFB), but failed to reduce the number of SPLI fibers in the BAL, and (2) the destruction of the BAL caused a decrease in SPLI fibers in the perifornical area rostral to the lesion, but failed to reduce the number of SPLI fibers in the MFB. These facts further suggest that ascending SPLI fibers from the BAL travel in the perifornical area and those from the TLD pass through the MFB. It should be noted that a few SPLI fibers remained intact following the simultaneous destruction of the BAL and TLD. The present study suggests that these remaining SPLI fibers might be innervated by intrinsic SPLI cells. In support of this, several SPLI cells were detected in the septal area after colchicine pretreatm

ISSN:0092-7317    

DOI:10.1002/cne.902120305

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThis study describes the Cytoarchitecture and neuronal morphology of the interstitial nucleus of Cajal (INC) in the cat. In addition, the efferent projections of this nucleus to the spinal cord and inferior olive were studied by retrograde labelling with horseradish peroxidase (HRP).The INC was shown to extend rostrocaudally for slightly more than 2 mm. Caudally, the nucleus consists of a small number of loosely aggregated neurons lying lateral to the ventral periaqueductal gray matter at a rostrocaudal level corresponding to the rostral one‐fifth of the somatic cell columns of the oculomotor nucleus. Rostrally, the INC increases in size and reaches its maximum development in its rostral half, where it lies ventro‐lateral to the nucleus of Darkschewitsch (ND). Rostrally the INC is bounded by the dorsoventrally aligned fibres of the fasciculus retroflexus.Two groups of neurons could be distinguished within the INC in both normal and HRP‐injected material. One group consists of a relatively small number of large, oval, pyramidal, fusiform, or multipolar neurons with mean dimensions of 40 × 26 μm The second group consists of numerous small to medium‐sized neurons with mean dimensions of 20 × 14 μm. Large neurons and some cells of the second group contain substantial amounts of Nissl substance throughout their perikarya. Some medium‐sized to small neurons exhibit indentations in their nuclei, and glial cells are often apposed to their cell membranes. Golgi‐Kop sch preparations taken from kitten showed that INC neurons possess sparsely branched, radiating dendritic trees with few spinous processes. The majority of INC neurons retrogradely labelled with HRP exhibited similar dendritic patterns.Injections of HRP into lesions at cervical, thoracic, or lumbar levels of the spinal cord resulted in retrograde labelling of neurons of all sizes and shapes throughout the entire length of the INC. However, the greatest number of HRP‐labelled cells in INC were observed subsequent to injections of the enzyme into cervical levels of the cord. Following injections of HRP into the inferior olive only small to medium‐sized neurons were labelled in the nucleus, the majority of which are located in rostral levels of the INC. A substantial olivary projection was observed to originate in the nucleus of Darkschewitsch (ND) and the nucleus parafascicularis (NPF). The sizes of the projections from these two nuclei to the inferior olive appeared to be much larger than that from the INC. Smaller numbers of neurons were also observed in the rostral parvocellular red nucleus (RN) and mesencephalic reticu

ISSN:0092-7317    

DOI:10.1002/cne.902120306

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractNeurons in the lateral and basolateral nuclei of the rat amygdala were studied using Golgi‐Kopsch and rapid Golgi techniques. According to differences in perikaryal, dendritic, and axonal morphology, three main neuronal classes are recognized. Class I neurons, the predominant cell type in both nuclei, are large, spiny neurons that vary in size in different subdivisions of the lateral and basolateral nuclei. These neurons often have a pyramidal shape, exhibiting one or two thick “apical” dendrites and several thinner “basal” dendrites. Axons of class I neurons, which appear to pass out of the nucleus of origin, usually give off several collaterals that arborize modestly in the vicinity of the cell. Class II neurons are smaller, ovoid cells that comprise approximately 5% of impregnated neurons. These neurons are characterized by spine‐sparse dendrites and fairly dense local axonal arborizations. Class II neurons may be classified as multipolar, bitufted, or bipolar, depending on dendritic branching pattern. Another type of class II neuron, the amygdaloid chandelier cell, is recognized by virtue of its distinctive axon. The chandelier cell axon gives off numerous collaterals that form nestlike entanglements exhibiting clusters of axonal varicosities. Isolated chandelierlike axons of undetermined origin were observed forming multiple contacts with initial segments of class I axons. Several small, spherical class III neurons with short, varicose dendrites were observed. Axons branch profusely to form a dense tangle of collaterals in the vicinity of the cell. Both axons and dendrites establish numerous contacts with class I dendrites. This investigation, the first detailed Golgi study of the basolateral amygdala of the rat, reveals that the cytoarchitecture of this brain region in the rat is basically similar to that of the opossum and other mammals. Morphologic details described in this report should be useful in the interpretation of ultrastructural, immunocytochemical, and electro‐physiological studies of the basolat

ISSN:0092-7317    

DOI:10.1002/cne.902120307

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractConnections between the right and left cochlear nuclei were studied with retrograde and anterograde axonal transport techniques. Large, multipolar neurons in the anterior and posterior divisions of the anteroventral cochlear nucleus and in the posteroventral cochlear nucleus project to the ventral and dorsal cochlear nuclei on the opposite side. In addition, giant cells in the deep layers of the dorsal cochlear nucleus project to the contra‐lateral posteroventral cochlear nucleus and possibly also to the contralateral dorsal cochlear nucleus. The pattern of terminal distribution of the crossed connections was determined by using the anterograde axonal transport of horseradish peroxidase‐labelled wheat germ lectin. Although no part of the cochlear nuclear complex is completely free of anterograde label, the densest labelling is found in the anterior division of the anteroventral cochlear nucleus, throughout the posteroventral cochlear nucleus (where it is closely associated with cell bodies), and in the fusiform and superficial layers of the dorsal cochlear nucleus.These direct synaptic connections from one cochlear nucleus to the other could play a significant role in processes that depend on binaural interactions within the central nervous sys

ISSN:0092-7317    

DOI:10.1002/cne.902120308

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902120309

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902120301

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY