摘要:

AbstractAfter lesions in the nucleus of the tractus solitarius (NTS) in cats and kittens, the termination of degenerating fibers was localized using the Nauta and the Fink‐Heimer techniques. The distribution of degenerating fibers was compared with that seen after lesions of the dorsal nucleus of the vagus (DNV) and after section of the ninth and tenth cranial nerves. The projection from the NTS is to the nucleus ambiguus (A), the other divisions of the NTS including the medial NTS and the ventrolateral NTS, the DNV, the medial reticular formation ventral to the NTS (probably the paramedian reticular nucleus), the nucleus intercalatus (INC), and the intermediate nucleus (INT). The probable functional significance of projections from the NTS to these medullary nuclei is discussed in relation to pathways of cardiovascular reflexes. Of particular note is the projection to the INT which may be part of a descending pathway to spinal cardiovascular neurons in the intermediolateral hor

ISSN:0092-7317    

DOI:10.1002/cne.901610202

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

年代:1975

数据来源: WILEY

摘要:

AbstractAnterograde degeneration studies have shown that the cochlear and vestibular receptor organs receive an efferent innervation from neurons in the brain stem. This pathway may provide a mechanism by which the CNS could modulate its own afferent input. The neurons which provide this innervation have so far escaped positive identification with methods which depend on retrograde cell changes after axotomy. In the present study, horseradish peroxidase (HRP) was injected into the labryinths of kittens and after allowing 24 hours for the retrograde axonal transport of this tracer, its presence in neurons of the brain stem was demonstrated histochemically. Because there is evidence that the efferent innervation of the labyrinth is cholinergic, acetylcholinesterase (AChE) was also demonstrated histochemically in the same or in adjacent tissue sections. Neurons labelled with HRP were found bilaterally in most periolivary cell groups of the superior olivary complex (cochlear efferents) and in the parvocellular reticular nucleus lateral to the abducens nucleus (vestibular efferents). Counts of labelled neurons yielded estimated totals of 1,700–1,800 cochlear and 400–500 vestibular efferent neurons. Approximately 60% of the neurons in each total were located on the side ipsilateral to the injection. The distribution of HRP‐labelled neurons was virtually identical to that of AChE‐positive neurons found in adjacent sections, and in those regions with predominantly ipsilateral or contralateral projections, there was an approximate correspondence in number of HRP‐ and AChE‐positive neurons. In tissue sections processed successively for demonstration of HRP and AChE, virtually all HRP‐labelled neurons were found to be AChE‐positive. These findings suggest that a number of current conceptions regarding labyrinthine efferent systems ma

ISSN:0092-7317    

DOI:10.1002/cne.901610203

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

年代:1975

数据来源: WILEY

摘要:

AbstractTwo normally‐reared dogs and five dogs reared with monocular eyelid closure were studied. The two normal dogs and three of the deprived dogs were tested with a perimetry technique for the extent of behavioral visual field, and all of the dogs were studied histologically to determine the size of cell somata in the lateral geniculate nucleus.Behaviorally, the normal dogs saw with each eye approximately from 120° ipsilateral to 30° contralateral. The deprived dogs had a normal field of view for the non‐deprived eye, but with the deprived eye they saw only in the monocular segment (i.e., approximately 120° to 30° ipsilateral).Histologically, geniculate cells in the monocular segment of deprived dogs were of normal size. In the deprived laminae of the binocular segment, however, cells averaged about two‐thirds normal size, and in non‐deprived laminae of this segment, neurons were hypertrophied. The hypertrophy was greater for cells in lamina A (40%) than for those in lamina A1 (17%).These data indicate that in monocularly deprived dogs, the monocular segment of the visual system develops normally, but the binocular segment does not. Therefore, we conclude that binocular competition operates in the developing dog's visual system much as it does i

ISSN:0092-7317    

DOI:10.1002/cne.901610204

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

年代:1975

数据来源: WILEY

摘要:

AbstractYoung dogs (6–14 weeks) were perfused with buffered aldehydes by standard techniques. The inferior medullary velum and tela choroidea were removed intact from the fourth ventricle, post‐osmicated, dehydrated, critical point dried, coated with palladium‐gold and examined in a Cambridge Stereoscan S4 scanning electron microscope. Selected samples after thorough scanning were routinely prepared for transmission electron microscopy (TEM).This study depicts numerous epiplexus (Kolmer cell) macrophages that exhibit extreme polymorphism. Because of the pleomorphic nature of these cells and their processes, classification based on external morphology is not practical. TEM shows their internal structure to be that of a macrophage. Bleb‐like structures and bulbous projections appear to emerge from certain ependymal cell surfaces which seem to be completely or partially devoid o

ISSN:0092-7317    

DOI:10.1002/cne.901610205

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

年代:1975

数据来源: WILEY

摘要:

AbstractThis study demonstrates partially overlapping fiber termination areas in the inferior olive originating from the dorsal column nuclei and the spinal cord.Based on the distribution of the terminations the dorsal accessory olive can be divided into a rostral and a caudal part. In the caudal part terminations are found of fibers originating in the contralateral gracile nucleus and in the lumbar and cervical spinal cord. Terminations in the rostro‐medial part of the dorsal accessory olive arise from the contralateral internal cuneate nucleus and from the opposite intermediate grey at C.1. Fibers from more caudal regions of the internal cuneate nucleus terminate in the dorsal accessory olive caudal to those originating from more rostral regions of this nucleus. The gracile nucleus and the lumbar spinal cord project to the rostro‐lateral portion of the dorsal accessory olive.The terminations in the medial accessory olive from the lumbar spino‐olivary fibers are found in a laterally located zone in the caudal one‐third of the nucleus. This spino‐olivary termination area extends more rostrally and medially after interruption of the cervical spino‐olivary fibers. Fibers from the contralateral gracile nucleus terminate in a medial zone in the caudal half of the medial accessory olive, while terminations of the contralateral internal cuneate nucleus are found at a more rostral level in the medial part of the medial accessory olive.Connections between the inferior olive and the caudal part of the spinal trigeminal nucleus, the lateral cervical nucleus and the cervical dorsal horn could not be d

ISSN:0092-7317    

DOI:10.1002/cne.901610206

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

年代:1975

数据来源: WILEY

摘要:

AbstractSources of telencephalic afferents were examined in two species of frogs,Rana catesbeianaandRana pipiens, by study of anterograde degeneration resulting from hemisection of the brain at the isthmus or at the caudal border of the thalamus and from electrolytic lesions in various portions of the diencephalon. The results indicate that some telencephalic afferents arise from levels caudal to the isthmus, that some striatal afferents arise from the level between the isthmus and the caudal border of the thalamus, and that a projection to the ipsilateral striatum arises from the anterior and/or middle portions of the dorsal thalamus. Diencephalic projections to pallial portions of the hemisphere were also observed. These results demonstrate substantial non‐olfactory afferent projections to the telencephalon in ranid frog

ISSN:0092-7317    

DOI:10.1002/cne.901610207

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

年代:1975

数据来源: WILEY

摘要:

AbstractBrain tissue was examined for morphological changes at 12 and 16 months after focal irradiation of the brain in female mice. Irradiation was performed with deuteron beams derived from the 60‐inch Brookhaven cyclotron at a rate of 1925 rad second−1through an anti‐Bragg device which produced uniform exposure. Experimental animals received a dose of 10,000 rad, covering a 9 × 5 mm area over the skull and extending into the brain for a depth of about 2 mm. An additional group of animals served as sham‐irradiated controls. Histological studies revealed extensive cell loss, vacuolation, and prominent vascular changes in irradiated regions of the brain at 16 months postirradiation. Ultrastructural examination of brain tissue at 12 and 16 months after irradiation revealed the presence of unusual elongated mitochondria with parallel arrays of cristae. Altered mitochondria were more prevalent at the longer post‐irradiatio

ISSN:0092-7317    

DOI:10.1002/cne.901610208

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

年代:1975

数据来源: WILEY

摘要:

AbstractIn order to determine whether there is a rubrothalamic projection in the rhesus monkey, the ascending degeneration resulting from electrolytic lesions made in the red nucleus and adjacent mesencephalon in animals surviving at least one year after bilateral interruption of the superior cerebellar peduncles (PCS) was studied by means of the Fink‐Heimer technique. In a necessary preliminary step it was shown that virtually all of the degeneration disappeared from the thalamus within twelve months after PCS interruption so that degeneration resulting from the subsequent electrolytic mesencephalic lesions could be attributed to interruption of non‐cerebellascending fibres.The results show that degeneration was present in the thalamus following the electrolytic mesencephalic‐diencephalic lesions but it could be accounted for on the basis of damage either to residual PCS fibres, to somatosensory pathways, to intrathalamic connections or to cell groups or projection fibres of the reticular formation, substantia nigra of globus pallidus. It is concluded that there is no direct rubrothalamic projection in the monkey and, in particular, no evidence of a projection from the red nucleus to the ventral lateral of ventral anterior thalamic nuclei.The results also indicate that the mesencephalic reticular formation is the main source of ascending afferents to the nucleus reticularis thalami. Some observations were made concerning nigrostriatal and nigrothalamic projections.Retrograde cell changes resulting from unilateral lesions made caudal to the red nucleus were studied in three animals. The observed cell changes are interpreted as being consistent with the conclusion that there is no rubrothalamic proje

ISSN:0092-7317    

DOI:10.1002/cne.901610209

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

年代:1975

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901610201

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

年代:1975

数据来源: WILEY