摘要:

AbstractAttempts were made to: (1) define the regions of origin of the ansa lenticularis (AL) and the lenticular fasciculus (LF), and (2) determine if particular regions of the medial pallidal segment (MPS) project in an organized fashion to thalamic nuclei. The MPS was divided into rostral and caudal (by a plane through the LF), dorsal and ventral (by an appropriate plane), and medial and lateral (by the accessory medullary lamina) parts. Attempts were made to categorize various lesions of the MPS and degeneration was studied in transverse, sagittal and horizontal sections stained by the Nauta and Wiitanen technics. Corresponding Nissl‐stained sections were used to delineate thalamic nuclei.Localized lesions in portions of the MPS (11 rostral and 10 caudal) were worthy of anatomical analysis in 21 monkeys. Data support the thesis that fibers of the AL arise predominantly from the outer part of the MPS and pass ventrally and medially through portions of the inner part of the MPS to their site of emergence. Fibers of the LF appear to arise from the inner part of the MPS and project dorsomedially through the internal capsule.Pallidothalamic projections to the rostral ventral tier thalamic nuclei [the ventral anterior (VApc) and the ventral lateral (VLo)] appear topographically organized in three cardinal dimensions. Rostral parts of the MPS project pre‐dominantly to parts of VApc, while caudal parts of the MPS project primarily to parts of VLo. There also is a dorsoventral and mediolateral correspondence in the pallidal projection to VApc and VLo which exhibits overlap. Pallidothalamic projections to the contromedian nucleus (CM) terminate preponderantly in rostral and medial regions of the nucleus, and there appears to be a definite correspondence between parts of the MPS and parts of CM, only in the dorsoventral dimens

ISSN:0092-7317    

DOI:10.1002/cne.901510302

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe response of oligodendrocytes, astrocytes, microglia, and pericytes to sciatic neurectomy in young adult rats was studied from 1μ Epon sections for quantitative cell counts and autoradiography. Two hours after an IP injection of3H‐thymidine animals were killed by aldehyde perfusion at survival periods of 2, 4, 7, and 14 days postoperative (dpo).At 2 dpo there was a marked increase in the number of labeled microglial cell nuclei and mitotic figures on the experimental side. This activation appeared to involve most of the “resting” microglia, which comprise about 6% of the total neuroglia in the normal ventral horn. A significant numerical increase (over fourfold) in perineuronal and total microglia was seen at 4 dpo followed by a gradual decline. Other findings include minimal chromatolysis in ventral horn neurons, contralateral effects, and a slight proliferative response in and around the central canal. A response was not apparent in the other neuroglia, pericytes, or mononuclear leukocytes. The relationship of the microglia to the multipotential glia of neuroectodermal origin is cons

ISSN:0092-7317    

DOI:10.1002/cne.901510303

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe response of oligodendrocytes, astrocytes, multipotential glia (MPG), and pericytes to sciatic neurectomy in young adult rats was studied by electron microscopy. Animals were perfused with aldehyde fixative at 2, 4, 7, and 14 days postoperative (dpo).Neuronal changes were slight and there was no apparent response in either oligodendrocytes or pericytes. Typical reactive changes observed in the astrocytes included an increase in glial filament bundles and microtubles. At 2 dpo mitotic cells were observed and by 4 dpo many MPG were located around affected neuron cell bodies apparently isolating them. The MPG processes formed overlapping sheets of processes between neurons and the elements of the neuropil. Hence synaptic boutons were displaced from the surfaces of the ensheathed neurons, but phagocytosis of synaptic boutons was rarely observed. The role and origin of the MPG and their similarity to microglia are discussed.

ISSN:0092-7317    

DOI:10.1002/cne.901510304

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe proximal portion of mitral cell axons was examined in electron microscopic serial sections and Golgi impregnations of mouse embryos on the fifteenth day of gestation (E15), E16, postnatal day one (P1), and P4. During this time the cell body of developing mitral cells appears to transform from tangential to radial orientation and then migrate peripherally while the tangential axon remains relatively fixed. In E15, E16 and P1 animals, electron microscopy of most radial mitral cells reveals that the microtubules of the axon proper are continued as a bundle of approximately the same diameter through the voluminous subnuclear cytoplasm to one side of the nucleus. The rest of the subnuclear cytoplasm is nearly devoid of microtubules and contains only free ribosomes and an occasional mitochondrion. It is suggested that the position of the axon is determined within the perikaryon by a bundle of microtubules; the nucleus and rest of the subnuclear cytoplasm then migrates peripherally leaving only a relatively thin axon. If some of the perikaryal cytoplasm failed to migrate peripherally, a bleb or process might be left, as in fact has been observed in Golgi impregnations and electron microscopy. We have also examined the ultrastructure of the developing axon initial segment, in cross‐sections of the axons from E15 to P4, as well as in longitudinal serial sections. Fascicles of closely apposed microtubules have been noted in some advanced mitral cells at E15 and E16, and by P1 such fascicles are common and well developed in most mitral cells. In P1 animals some mitral cell initial segments show a faint and patchy dense undercoating of the axolemma, but many axons at this time appear to completely lack this feature. By P4 nearly all initial segments show a fairly well developed dense undercoating. In general, therefore, the development of fascicles of closely apposed microtubules precedes the elaboration of the dense undercoating of the axolemm

ISSN:0092-7317    

DOI:10.1002/cne.901510305

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

年代:1973

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901510301

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

年代:1973

数据来源: WILEY