摘要:

AbstractTransection of the pituitary stalk caused rapid and severe degeneration of the hypothalamo‐hypophysial nerve tract distal to the operation site. When a barrier had been inserted to prevent reunion of the stalk this degeneration was permanent. All nerve fibers and stainable neurosecretory material (NSM) disappeared. When a barrier was not used the initial degeneration was followed by regeneration. From two weeks after operation new nerve fibers from the hypothalamus, carrying NSM, were found growing through the scar and down the degenerated lower infundibular stem towards the infundibular process, which was fully re‐innervated by the end of a year. The re‐innervated lower infundibular stem contained an abnormally large amount of NSM. In many cases an outgrowth of nerve fibers from the regenerating tract had invaded the rostral end of pars distalis; these also were surrounded by NSM. Another unusual feature often seen was an ectopic infundibular process which had developed not far below the site of operation.In its capacity for vigorous regeneration the hypothalamo‐hypophysial nerve tract appears to be unique among tracts of the central nervous system. It is suggested that this regenerative capacity may be related to the fact that this tract is composed of non‐myelinated ner

ISSN:0092-7317    

DOI:10.1002/cne.901350202

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

年代:1969

数据来源: WILEY

摘要:

AbstractGanglion cell changes were studied in 25 monkeys following systematic section of spinal and cranial sensory nerves proximal or distal to the ganglion. Ganglion cells were studied in Nissl preparations while central degeneration was studied in Nauta‐Gygax stained sections. Morphological characteristics of normal ganglia were studied in unoperated controls.In normal ganglia three categories of cells were identified: (1) A predominant largecelled group (ranging from 20 to 100 μ), (2) small dark cells, and (3) a small number of “atypical” cells.Division of nerves proximal to ganglia produced no cellular changes in most cases; changes attributed to relative ischemia occurred in a few ganglia. Centrally projecting fibers of sectioned nerves were degenerated.Division of sensory nerves distal to ganglia produced profuse chromatolytic changes in cells of all sizes and types within ganglia but no central degeneration. Cervical section of the vagus produced chromatolytic cell changes in the inferior ganglion and a small portion of the superior ganglion unrelated to the auricular nerve. Section of the facial nerve distal to the geniculate ganglion produced chromatolysis in approximately half of the ganglion cells. An accessory trigeminal ganglion, composed of cells of autonomic type, was found distal to the trigeminal ganglion in association with the third division of the nerve.Severance of nerve fibers distal to sensory ganglia eliminates peripheral neurotrophic influences necessary for the growth and maintenance of the ganglion cell. It is postulated that the integrity of this influence is sufficient to sustain sensory ganglion cells after their central processes have been sec

ISSN:0092-7317    

DOI:10.1002/cne.901350203

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe effect of visual deprivation on the morphology of the primary and secondary visual centers was studied. The deprivation was achieved by unilateral lidsuture in 14 or 15 day old white rats before eye opening. The animals were kept for 8‐9 weeks in larger cages where they were exposed to different kinds of visual stimulation and had greater movement opportunity. The asymmetry was revealed by means of volume measurement and cell counting. No changes could be found in the optic tract and superior colliculus. The volume differences on the side supplied by the deprived eye were found in the dorsal part of the lateral geniculate body −5.07%, and in the primary visual area −16.0%. Cell counting revealed asymmetry in the dorsal part of the lateral geniculate body −13.5%, as well as in the pulvinar −7.0%. No consistent difference in cell density could be found in cortical Iayer V of area 17, whereas in layer IV there were relatively more cells +11.5% on the side connected with the deprived eye. The changes in different centers related to the visual pathway were of different intensity according to the proposed role in transmitting different kinds of visual in

ISSN:0092-7317    

DOI:10.1002/cne.901350204

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

年代:1969

数据来源: WILEY

摘要:

AbstractAn electron microscopic study has been undertaken of the upper layers of the superior colliculus, into which run fibers from the retina and visual cortex. Study of the normal synaptic patterns shows large numbers of serial synapses, particularly near the surface of the colliculus. The presynaptic components usually contain round vesicles and the intermediate profiles always contain flattened vesicles. The latter may be dendrites, dendrite‐like or dilatations of such profiles. Degeneration studies indicate that optic terminals are especially dense near the surface and that they are often the presynaptic terminal of a serial synapse. Very few optic terminals occur in the stratum opticum. Cortical afferents from the visual area mostly end deep in the stratum griseum superficiale, and in superficial stratum opticum, usually on small clear profiles.Studies of the progress of degeneration indicate that optic terminals first show a predominantly neurofilamentous and associated glycogen reaction, and later a predominantly electron dense reaction. Cortical terminals show an initial dense reaction, with occasional neurofilamentous endings. These time course fit well with light microscope data from Nauta and Glees stained material.The synaptic patterns described here closely resemble patterns described in retina and dorsal lateral geniculate body. How these reflect functional similarities has yet to be resolve

ISSN:0092-7317    

DOI:10.1002/cne.901350205

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

年代:1969

数据来源: WILEY

摘要:

AbstractEfferent tectal pathways have been determined for the opossum,Didelphis virginiana, by employing the Nauta‐Gygax technique ('54) on animals with tectal lesions of varying sizes. The superior colliculus projected tectothalamic fascicles to the suprageniculate nucleus, the central nucleus of the medial geniculate body, the lateral posterior thalamus, the pretectal nucleus, the ventral lateral geniculate nucleus, the fields of Forel and zona incerta, the parafascicular complex, the paracentral thalamic nucleus and in some cases to restricted areas of the anterior thalamus. Degenerating fibers from superior collicular lesions showed profuse distribution to the deeper layers of the superior colliculus on both sides and to the midbrain tegmentum, but only minimally to the red nucleus and substantia nigra. Fibers of tectal origin did not distribute to the motor nuclei of the oculomotor or trochlear nerves. At pontine levels, efferent fascicles from the superior colliculus were present as an ipsilateral tectopontine and tectobulbar tract and as a crossed predorsal bundle. The tectopontine tract ended mostly within the lateral and ventral basal pontine nuclei, whereas the ipsilateral tectobulbar tract distributed to certain specific areas of the reticular formation throughout the pons and medulla, minimally to the most medial portion of the motor nucleus of the facial nerve and to the nucleus of the inferior olive. The predorsal tract contributed fascicles to certain nuclei of the pontine raphe, extensively to the medial reticular formation of the pons, to the central and ventral motor tegmental nuclei of the reticular formation within the pons and medulla, to the paraabducens region, minimally to cells within restricted portions of the motor nucleus of the facial nerve, to certail specific regions of the caudal medulla and to the cervical cord as far caudally as the fourth segment. The tectospinal fascicles were few but some ended related to the spinal accessory nucleus and the ventral medial nucleus of the ventral horn.Lesions of the inferior colliculus resulted in degenerating fibers which distributed rostrally to the rostral nucleus of the lateral lemniscus and parabrachial region, to the suprageniculate nucleus, the parabigeminal nucleus and to the central nucleus of the medial geniculate body. The inferior colliculus also contributed fibers to the ipsilateral tectopontine and tectobulbar tracts. The latter bundle was traced as far caudally as the medulla and may arise from cells of the superior colliculus which are situated dorsal to the nucleus of the inferior colliculu

ISSN:0092-7317    

DOI:10.1002/cne.901350206

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

年代:1969

数据来源: WILEY

摘要:

AbstractCat brains were fixed by vascular perfusion with glutaraldehyde and paraformaldehyde and the entopeduncular nucleus was examined by electron microscopy. The fine structure of most neurons in this region does not significantly differ from earlier descriptions of large neurons. Distinctive features of perikarya and dendrites include juxtanuclear Nissl bodies, unique lamellar configurations composed of agranular cisternae separated by thin layers of dense granular matrix and continuous with the granular endoplasmic reticulum, localized swellings of dendrites, and dendritic branchlets or gemmules which invaginate a single nerve terminal. Cell surfaces are ensheathed by interdigitating nerve terminals and glial lamellae. Two types of endings are distinguished on the basis of their diameter and the size of their synaptic vesicles. Further division depends on distribution of the vesicles within a terminal, where the synapses occur, and the presence of postsynaptic bodies. Most terminals are about one micron and contain closely packed synaptic vesicles measuring 515 Å (S. D. 72.7 Å). Larger terminals containing fewer smaller (312 Å) synaptic vesicles and neurofilaments or neurotubules near the periphery have been interpreted asboutons‐en‐passage.It is suggested that different afferent projections end in a similar manner on restricted portions of the neuronal surfaces in the entopeduncular n

ISSN:0092-7317    

DOI:10.1002/cne.901350207

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.901350201

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

年代:1969

数据来源: WILEY