摘要:

AbstractUnilateral spinal lesions were made in six Macaques; in two, the bulbar pyramid was sectioned contralaterally. In four Macaques with chronic pyramidal section, contralateral spinal lesions were made. The effect of each lesion separately and of the combined lesions upon the locomotor status of the animals was evaluated behaviorally, by electromyography and the lesions studied histologically after two years' survival.Spinal lesions provoked changes in resistance to passive stretch and tendon reflexes primarily, and changes in movement secondarily: when hypertonus appeared, movements in opposing muscles were restricted, whereas movements opposing muscles were restricted, whereas movements opposed by muscles with decreased tone were hypermetric. Spinal lesions greatly altered the paresis provoked by pyramidotomy: small ventrolateral lesions restored “contact” placing, improved stepping and hopping and made the hypotonic (“pyramidal”) limb hypertonic. Execution of movements was poor, however, poorest in an animal with combined pyramidal and ventral funiculus lesion. The importance of extrapyramidal tracts in return of function following pyramidotomy was demonstrated in relation (a) to the size of the spinal lesion and (b) to its cross‐sectional location.Gross sequential movement of muscles normally fixating the limb appears when the pyramid is cut. These movements are greatly impaired when spinal lesions are added, and the usual grouping of synergists is disrupted. Fixation of the limb represents the integration of extrapyramidally activated, pyramidally inhibited synergistic contractions upon which discrete usage of distal muscl

ISSN:0092-7317    

DOI:10.1002/cne.901350102

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe ascending projections of the vestibular nuclei were studied with the selective silver methods of Nauta‐Gygax (Nauta,'57), Voneida ('67) and Fink et al. ('67) in macaque, baboon and chimpanzee. Degenerated axons pass from lesions in the vestibular nuclei into the medial medullary and pontine tegmentum bilaterally, the abducens nuclei, the contralateral vestibular complex and in the medial longitudinal fasciculus to the nuclei of the III and IV nerves. A few fibers pass rostral to the oculomotor complex into the interstitial nuclei of Cajal, the nuclei of Darkshewitsch and the nuclei of the posterior commissure. No degenerated fibers originating in vestibular nuclear lesions were observed to ascend rostral to the level of the posterior commissure. Degenerated fibers rostral to this level could be traced, in sagittal, horizontal and frontal sections, to incidental damage to the superior cerebellar peduncle and the posterior column nuclei. Damage to the acoustic striae produced ascending degeneration in the auditory system, but this did not pass rostral to the inferior colliculus. The incidentally damaged tracts could be seen, in sections in three planes, to be separate in their course and terminations from the fibers ascending from the vestibular nuclei in the medial longitudinal fasciculus.The experimental evidence lends no support to the supposition that direct secondary vestibular connections to the diencephalon exist. Previous anatomical descriptions of direct vestibulothalamic connections appear to result from failure to discriminate between fibers originating in the vestibular nuclei and fibers arising in adjacent regions. Vestibular impulses reaching the diencephalon must pass over third or higher order neurons after synapse at lower level

ISSN:0092-7317    

DOI:10.1002/cne.901350103

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe corpus callosum of 60–80 gm male rats was processed by the weak silver carbonate method of del Rio‐Hortega for the detection of microglia in the light microscope. Because of the opacity of the metal stain taken up by these cells, they could be recognized in the electron microscope. The characteristic features of microglia were thus found to be a small nucleus in which dark chromatin contrasts with light nucleoplasm, and a cytoplasm containing dense bodies (presumed to be lysosomes) and poor in endoplasmic reticulum. After gaining experience with microglia in the electron microscope, it became possible to recognize their features in 0.5–1 μ thick toluidine blue stained Epon sections examined in the light microscope.In the electron microscope, some microglia are found within expansions of the basement membrane of capillaries (pericytal microglia); they usually have little cytoplasm, few dense bodies and few processes. There is evidence that these cells can break out of their basement membrane enclosure and enter the brain tissue proper. There, they scatter singly between other cells and fibers. These cells (interstitial microglia) send of long processes. They may contain numerous dense bodies and be surrounded by irregular spaces (suggesting the existence of surface activity). These observations support the classical view of microglia as brain macrophages.Microglia constitute 5.5% of the glial population of the corpus callosum. After injection of3H‐thymidine and radioautography in the light or electron microscope, none showed labeling. Hence, it is presumed that microglia do not proliferate under normal co

ISSN:0092-7317    

DOI:10.1002/cne.901350104

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

年代:1969

数据来源: WILEY

摘要:

AbstractLong‐term transneuronal changes have been investigated in the lateral geniculate nucleus of the squirrel monkey (Saimiri sciureus). Recent reports that the parvocellular portion of that nucleus is laminated in typical primate fashion are verified. Measurements of changes in cell size indicate that, (a) cells in the parvocellular layers show greater shrinkage than do cells in the magnocellular layers and, (b) there is little change in cell size for enucleation terms of one versus two years. Measurements are also presented which suggest that lateral geniculate cells retaining retinal input in the monocular squirrel monkey show an increase in cross‐sectional area so that enucleation may lead to both atrophic and hypertrophic chan

ISSN:0092-7317    

DOI:10.1002/cne.901350105

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

年代:1969

数据来源: WILEY

摘要:

AbstractAn area under the ependyma of the infundibulum in jungle fowl hens enlarges progressively during incubation. The structure is reduced in size and altered in appearance in laying hens, regressed in nonlaying hens, and absent in males. Enlargement of the structure does not depend on increasing or decreasing day length. The area did not enlarge in jungle fowl receiving injections of prolactin. No similar structure was found in incubating house sparrows, rock doves, or ring‐necked pheasant.Histological and histochemical examination of the enlarged area led to the tentative conclusion that it may represent a neurohaemal depot for ergones from the infundibular hypothalamic nuclei and may be evolved from a structure homologous with the neurohypophysis of lower vertebrate

ISSN:0092-7317    

DOI:10.1002/cne.901350106

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

年代:1969

数据来源: WILEY

摘要:

AbstractThis study of the fine structure of the neuroglia in the spinal cord of the newt,Triturus viridescens, has permitted the identification of three types of glial elements. One type is the ependymal cell whose processes are rich in filaments and glycogen and end on the pia in the deeper portion of the fissures of the cord. The two other types of glial cells display some morphological similarities to typical mammalian neuroglia although they appear to be more primitive. These are the astrocytes and oligodendrocytes. The astrocytes contain glial filaments, glycogen, specialized mitochondria, few ribosomes, and probably send end feet to the surface of the cord and to the intramedullary vessels. The oligodendrocytes present some variation in morphology but always exhibit an abundance of ribosomes. They are located either near the neurons, the intramedullary vessels, the pia, or the myelin sheath.

ISSN:0092-7317    

DOI:10.1002/cne.901350107

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

年代:1969

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901350101

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

年代:1969

数据来源: WILEY