摘要:

AbstractThe central projections of the chorda tympani nerve in the duck were studied by means of the Fink‐Heimer technique. Following section of the VIIth nerve proximal to the geniculate ganglion terminal projections of the CT are found in the sensory nucleus N VII (sVIId) on the dorsum of the descending trigeminal root, the n. presulcalis anterior solitarii, the n. sulcalis anterior solitarii p. dorsalis and p. ventralis, and the n. ventrolateralis anterior solitarii (Vla). Small quantities of terminal degeneration are also found in the n. intermedius anterior and the lateral substantia gelatinosa of the solitary complex. A number of fibers decussate to terminate contralaterally in corresponding portions of the opposite solitary complex. Comparison with data of the pigeon reveals a limited overlap of projections of the chorda tympani nerve and of the nodose ganglion, respectively, in the dorsal and ventral parts of the n. sulcalis anterior. We suggest that the regions sVIId and Vla alone may convey gustatory informatio

ISSN:0092-7317    

DOI:10.1002/cne.901700402

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

AbstractThe conduction velocity and axon diameter of medial and lateral giant axons in lobsters was followed during growth from early juvenile (13 mm) to adult (250 mm) forms. In both axons, conduction velocity increased more than 4‐fold in the growth period examined. Correlated with the increase in conduction velocity is an increase in axon diameter and the relationship between these two parameters is expressed by the equation CV = krx, where x equals 0.5 for the lateral and 0.7 for the medial giant axons. The sheath surrounding the giant axons also increases in size during growth with that of the medial giant axon being considerably thicker than that of the lateral giant axon. The significance of the increase in axon diameters is to increase conduction velocity and thereby reduce the latency of the escape response mediated by these giant axon

ISSN:0092-7317    

DOI:10.1002/cne.901700403

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

AbstractIn the neocortex of the reeler mutant mouse, there is inversion in the normal relative positions of polymorphic and pyramidal cells and of large with respect to medium‐sized and small pyramidal cells. Granule cells are concentrated at a near‐normal mid‐cortical level in the mutant. As in the normal animal, and despite cell malposition in reeler, the principal tangential fiber system lies in the zone of polymorphic cells. Large fiber fascicles, known from experimental studies to be principally thalamo‐cortical afferents, enter the tangential fiber system in the polymorphic cell zone of both reeler and normal neocortex. In the mutant these fascicles must traverse the full width of the cortex to reach this fiber system in its superficial location. In both normal and mutant animals single fibers, again principally thalamo‐cortical afferents, pass from the principal tangential fiber system to ramify in a fiber feltwork in the zone of granule cells. In the mutant these descend whereas in the normal animal they ascend. Also, as in the normal mouse, single fibers pass radially between all levels of the mutant cortex and the central white matter. Regional variations in the character, the pattern of distribution and the relative prominence of homologous cell and fiber elements are closely parallel in reeler and normal. This suggests that cell differentiation and the tangential organization of reeler neocortex are normal despite cell malposition in t

ISSN:0092-7317    

DOI:10.1002/cne.901700404

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

AbstractThe tangential organization of the callosal system of interhemispheric connections, as judged by the distribution of axon terminals as well as by the distribution of cells of origin of callosal axons, is normal in the reeler mutant mouse. As in the normal animal connections between the two cerebral hemispheres are homotopic. In the reeler, as in the normal animal, medium‐sized pyramidal cells are, numerically speaking, the principal cells of origin of the callosal system. These lie superficially in the cortex of the normal animal but deep within the cortex of reeler. Callosal terminals are most densely concentrated at the cortical level of the small and medium‐sized pyramids in both reeler and normal animals. It is probable, therefore, that the same classes of neurons are interconnected by the callosal system in the normal and reeler mouse despite malposition of neurons in reeler. The pattern of intracortical distribution of terminals of callosal axons is evidently governed by the positions of their target ce

ISSN:0092-7317    

DOI:10.1002/cne.901700405

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

AbstractDuring the course of an investigation of the synaptic organization of the external cuneate nucleus (ECN) in the Sprague‐Dawley albino rat, the ultrastructural morphology of nodes of Ranvier in the neuropil has been studied.The majority of nodes observed have the basic morphological features of conventional central nodes but there is individual variation with regard to length, surface area and cytoplasmic organelles. In addition, nodes with multiple myelinated branches are observed.Some nodes of Ranvier were observed to form specialized synaptic boutons. Two types of nodal synaptic boutons were present; asimpletype and acomplextype. Simple nodal boutons were observed more frequently. These nodes usually synapse upon a single dendritic element; the portion of the node opposite the presynaptic area has a morphology similar to conventional nodes. Complex nodal boutons are of greater dimension than simple nodal boutons and are usually in contact with several neuronal elements. They may be presynaptic to dendritic shafts or spines and are occasionally observed to be postsynaptic to small axonic profiles, a synaptic relationship which, until this report, has not been demonstrated in the central nervous system (CNS).The possible functional significance of these observations is discusse

ISSN:0092-7317    

DOI:10.1002/cne.901700406

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

AbstractThe cytology of the superior olivary complex was studied in Nissl stained sections of eight human brainstems, including adult, infant and fetus, and in the brains of ten juvenile rhesus monkeys. The most prominent components of the superior olivary complex of primates were specifically investigated, i.e., the medial (SOM) and lateral (SOL) superior olivary nuclei. Cell counts of these segments were done in human brainstems. The adult SOM was comprised of an average of 11,428 (7,850–15,010) perikarya; the SOL contained an average of 3,923 (2,890–5,400) neurons. These findings indicate that the SOL contains as many cells as reported in other primates, and is not reduced. The SOL appears somewhat inconspicuous in the human because it is organized into as many as six clusters of cells rather than forming one well circumscribed configuration as in the monkey and cat.The total cell population of the SOM together with the SOL was approximately the same on each side of individual brains. If one segment was larger on one side than the opposite side, the other segment was correspondingly reduced to maintain the relative symmetry. This suggests that a single mechanism controls the cell complement of at least these two segments of the superior olivary comp

ISSN:0092-7317    

DOI:10.1002/cne.901700407

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

AbstractFollowing lesions of the dorsal column nuclei, spinal cord and sensorimotor cortex, anterograde degeneration was traced to a common target in the central midbrain: the intercollicular terminal zone. Although not all the midbrain projections of the three pathways are contained within this zone, it receives overlapping projections from each of the three body‐related somesthetic pathways studied. The intercollicular terminal zone covers the entirety of the external nucleus of the inferior colliculus and the intercollicular nucleus of Mehler, spilling over into adjacent parts of the central gray and deep layers of the superior colliculus. Little evidence of somatotopy in the somesthetic projections was disclosed, and bilateral input was found in each experimental case, regardless of the type of lesion. Golgi‐stained material was examined to explore the basis of the extensiveness of the terminal zone. These materials showed that the dendritic spread of neurons in the external nucleus of the inferior colliculus and the intercollicular nucleus, taken together, covers the entirety of the intercollicular terminal zone. That is, the dendrites invade the same portions of the central gray and deep layers of the superior colliculus which are covered by the terminal field. We conclude that a tripartite division of the sensory midbrain may be justified: with the somesthetic modality being represented anatomically in a fashion at least roughly analogous to that of vision and audit

ISSN:0092-7317    

DOI:10.1002/cne.901700408

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

AbstractThe cerebello‐olivary pathway in the cat has been examined using orthograde and retrograde neuroanatomical tracing techniques.The orthograde transport of3H‐leucine from injection sites in the deep cerebellar nuclei labeled dentate and interpositus projections to the rostral two‐thirds of the contralateral inferior olivary complex. These projections are topographically organized, with the dentate nucleus projecting to the principal olivary nucleus and the posterior and anterior interpositus nuclei projecting to the medial and dorsal accessory olives respectively. Fibers from the ventral half of the dentate nucleus terminate in the lateral bend and ventral lamina of the principal olive, whereas the medial and lateral parts of the dorsal half of the nucleus project to the medial and lateral regions of the dorsal lamina respectively. It is apparent that the more caudal parts of the interpositus nuclei project to areas of the medial and dorsal accessory olives near the caudal end of the principal olivary nucleus, whereas neurons in the more rostral parts of the interpositus nuclei project to the more rostral areas of the accessory olivary nuclei. A connection between the fastigial nucleus and the inferior olive could not be demonstrated.The retrograde transport of horseradish peroxidase (HRP) from injections sites in the inferior olive labeled cells throughout the contralateral dentate and interpositus nuclei. The labeled cells were especially numerous in the ventral parts of the dentate and posterior interpositus nuclei. These HRP‐positive neurons were consistently small (10–15 μ) ovoid or spindle‐shaped cells, with relatively large nuclei and light‐staining Nissl substance.This evidence strongly suggests that the cerebello‐olivary pathway originates from a population of small neurons in the dentate and interpositus nuclei and projects to specific, topographically defined areas in the contralatera

ISSN:0092-7317    

DOI:10.1002/cne.901700409

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901700401

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY