摘要:

AbstractThe cytoarchitecture of the dorsal nucleus praeeminentialis in two families of weakly electric fish (Eigenmannia viriscensandApteronotus albifrons) was examined in both Nissl and Golgi material, and an attempt was made to correlate this information with our data from HRP studies on the afferent and efferent connections of this nucleus.The n. praeeminentialis is an isthmic structure located dorsolateral to the lateral lemniscus and anterior to the eminentia granularis‐a subdivision of the archicerebellum of fish. The n. praeeminentialis can be divided into a large dorsal portion concerned with electroreception and a small ventral portion involved with the lateral line mechanoreception. The dorsal n. praeeminentialis consists of three parts: a pars medialis, a large pars principals (p.P.) and a narrow pars lateralis. The p.P. presents three zones: a dorsal, a central, and a ventral zone, which are reciprocally and topographically connected with the zones of the electroreceptive lateral line lobe (ELLL), medial ELLL with ventral zone, central ELLL with central zone, and lateral ELLL with dorsal zone. Several types of projection cells are present in the n. praeeminentialis: (a) neurons that show preferential orientation of theirlong dendritesin relation to the afferent fiber systems, (b) cells withwide dendritic fieldsradiating in all directions, and (c) cells withsmallpolarizeddendritic fieldstoward the incoming ELLL afferents.Interneurons are also identified, showing different axonal ramification patterns.The afferent and efferent fiber systems linking the n. praeeminentialis to ELLL, lobus caudalis (L.C.), and torus semicircularis (T.S.d.) point to the important position of this nucleus in the feedback loop of the electrosensory pathway. The complex processing within this nucleus is reminiscent of the feedback loops in the auditory syste

ISSN:0092-7317    

DOI:10.1002/cne.902210202

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe degree of accuracy with which regenerating preganglionic parasympathetic fibers can restore their original connections was examined in the frog,Rana pipiens. The normal motor pool of the vagus nerve was determined by labeling the vagal cardiac branch fibers with horseradish peroxidase (HRP). Cardiac neurons form a relatively compact subgroup within the rostral half of the vagal motor column and represent less than 5% of the total vagal motor pool.Five to 14 weeks after crushing the vagus nerve, HRP labeling revealed that a more extensive population of vagal motor neurons has reinnervated the cardiac branch. The regenerated cardiac motor neuron pool is about twice as numerous as normal but is still centered in the rostral half of the vagal motor column.These experiments show that regeneration of the cardiac branch of the vagus nerve is neither a random process nor one which is completely accurate. Some degree of accuracy is maintained during regeneration following a crush lesion. Neurons nearer the original cardiac motor pool are more likely to reinnervate the cardiac branch than are vagal motor neurons located at some distance from the original cardiac pool.

ISSN:0092-7317    

DOI:10.1002/cne.902210203

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

年代:1983

数据来源: WILEY

摘要:

AbstractThis study utilizes anterograde axonal transport of cobaltous‐lysine and conventional silver‐staining techniques to study the central projections of the horizontal semicircular canal branch of the VIII nerve within the vestibular nuclei of the carpet sharkCephaloscyllium isabella. Two major terminating axon fields were observed, one caudal and one rostral to the entrance of the VIII nerve, corresponding to the ventral vestibular nucleus and superior vestibular nucleus, respectively. Both fields appear to be located within the ventral portion of the nuclei indicating an apparent subdivision of the VIII nerve projections within the brainstem. The resolution of the sensitive cobalt tracer indicates the presence of both dendritic and pericellular termination of these primary afferent fibres. In the area immediately caudal to the entrance of the VIII nerve a number of labelled primary afferent fibres project to the ventral region of the intermediate nucleus. Other fibres follow the visceral sensory root VII and terminate proximal to the sulcus limitans of His within the dendritic field of the neurons of the nucleus magnocellularis. Some fibres turn ventromedially from the main group of the ascending fibres and terminate in the area of the inferior reticular format

ISSN:0092-7317    

DOI:10.1002/cne.902210204

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

年代:1983

数据来源: WILEY

摘要:

AbstractThis study utilizes retrograde axonal transport of cobaltous‐lysine, and conventional silver and Golgi staining techniques to study the abducens motor nucleus innervating the external rectus muscle of the carpet shark. The nucleus consists of 300–400 motoneurons located immediately ventrolateral to the medial longitudinal fasciculus (MLF), distributed over about 1.25 mm in a rostrocaudal direction at the level of exit of the VI nerve. The axons of the motoneurons form seven or eight discrete ventrally directed fascicles which, having exited from the brainstem, group together to form the abducens (VI) nerve. The motoneurons are on average about 16 μm in diameter, are bipolar, and their dendrites have a transverse orientation. Typically one set of dendrites penetrates the MLF and the other set extends ventrally into the reticular forma

ISSN:0092-7317    

DOI:10.1002/cne.902210205

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe superior temporal region (STR) in the rhesus monkey includes the circular sulcus (Cis), the supratemporal plane (STP), and the superior temporal gyrus (STG). Rostrally the STR is continuous with the periallocortices of the prepyriform and anterior insular regions; caudally it borders the isocortices of the inferior parietal lobule and the superior temporal sulcus. The STR contains 12 cytoarchitectonic areas: four fields on the Cis, four on the STP, and four on the STG. The sulcal fields (root fields) are adjacent to the insula and resemble it in the possession of a relatively strong layer V; the STP fields (core fields) are characterized by well‐developed layer IV; and the STG fields (belt fields) exhibit strong differentiation of layer III. In each line of fields the more rostral ones show relative prominence of the deeper layers, with increasing prominence of the superficial layers occurring caudad in a stepwise fashion.Analysis of the connectional organization of the fields within the STR suggests an assembly of four rostrocaudal stages, each composed of one field from each line–a root, a core, and a belt field. There is a specific arrangement of connections among the fields of a given stage and between fields in adjacent stages. Projections directed caudally from one field to another field in the adjacent stage arise in layers V and VI and terminate in the superficial layers (mainly layer I). Projections directed to a field in a rostrally adjacent stage arise from layer III neurons and terminate in layers III and IV, usually in columns. There is also a laminar specificity between fields lying within a given st

ISSN:0092-7317    

DOI:10.1002/cne.902210206

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe musculature and associated skeleton, peripheral nervous system, and central projections of motor and sensory neurones of the two basal (thoracic and coxal) segments of the shore crab leg (fifth pereiopod, P5) were examined in vivo and with methylene blue or cobalt staining.Each of the four main basal muscles, promotor/remotor, levator/depressor, controlling the thoracico‐coxal (T‐C) and coxo basal (C‐B) limb joints, respectively, comprises several more or less discrete fibre bundles (total 14), with little morphological segregation of different functional groups.The innervation to the basal leg region is carried in two nerve roots arising from the thoracic ganglion. The anterior Th‐Cx root carries both sensory and motor axons, while the posterior Th‐Cx root is purely motor. Three previously undescribed sensory branches (two “epidermal” nerves and an “accessory” branch), in addition to that innervating the coxobasal chordotonal receptor, have been found in the distal part of the anterior Th‐Cx root. Two clusters of 10 to 15 multipolar somata (diam. 30–125 μm) are located proximally at the bifurcation of the accessory nerve and distally where the latter enters the basipodite.The cell bodies (diameter 20–80 μm) of basal leg motoneurones (total ca. 30) lie in the dorsal cortex of the ganglion, with somata of functionally related motoneurones tending to form discrete structural groups. The morphology of individual motoneurones conforms to the general arthropod pattern. All are confined to the ipsilateral hemiganglion and their main neuropilar processes run parallel and in close apposition to each other with overlapping dendritic structures. Sensory projections arising from the CB chordotonal organ also ramify in the region of the neuropile invaded by motoneurones. The possible physiological significance of such structural associations within the CNS is discussed, as are the functional implications of basa

ISSN:0092-7317    

DOI:10.1002/cne.902210207

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe central projections of first‐order lateral line and octavus nerve afferents of the clearnose skate,Raja eglanteria, were, determined by nerve degeneration and horseradish peroxidase techniques. The octavolateralis area of the medulla, which receives these afferents, is organized into dorsal, intermediate, and ventral longitudinal columns of cells and neuropil. Fibers that innervate the electroreceptive sense organs enter the dorsal longitudinal column via the dorsal root of the anterior lateral line nerve and terminate within the dorsal nucleus. Mechanoreceptive fibers from neuromasts of the head and trunk are carried by the ventral root of the anterior lateral line nerve and posterior lateral line nerve, respectively. Both nerves enter the intermediate longitudinal column and terminate throughout the rostrocaudal extent of the intermediate nucleus. Fibers of the ventral root of the anterior lateral line nerve are confined to the medial portion of the intermediate nucleus and posterior lateral line nerve fibers to the lateral portion. In addition, ascending mechanoreceptive fibers from both head and trunk neuromasts project to the vestibulolateral lobe of the cerebellum.Octavus nerve afferents enter the medulla and terminate primarily within the four octaval nuclei that comprise the ventral longitudinal column. Rostrocaudally, these nuclei are the anterior, magnocellular, descending, and posterior octaval nuclei. A few ascending axons continue beyond the anterior octaval nucleus and course to the vestibulolateral lobe of the cerebellum. Some descending axons emanate from the descending octaval nucleus and course to the reticular formation and intermediate nucleus.Therefore, electroreceptive lateral line, mechanoreceptive lateral line, and octavus nerve afferents project ipsilaterally and terminate predominantly within separate medullary nuclei. The significance of octavus nerve projections to the intermediate nucleus and overlap of mechanoreceptive and octavus afferents within the vestibulolateral lobe of the cerebellum cannot be determined until it is known which fibers of the inner ear sense organs project to these areas.Retrograde transport of horseradish peroxidase results in the labeling of large multipolar cells, both ipsilaterally and contralaterally, within a column of gray that lies dorsolateral to the reticular formation. These cells are interpreted as the cells of origin of the efferent components of the anterior and posterior lateral line nerve

ISSN:0092-7317    

DOI:10.1002/cne.902210208

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

年代:1983

数据来源: WILEY

摘要:

AbstractOrthograde and retrograde labeling techniques were used to study the ontogenesis of transient cerebrocerebellar projections in kittens. Tritiated amino‐acid or horseradish peroxidase injections were made into the coronal gyms of the primary somatosensory cortex of kittens 1–70 postnatal days old. Orthogradely labeled axons were observed bilaterally in the superior and inferior cerebellar peduncles in kittens between 6 and 49 postnatal days of age. Most cerebrocerebellar axons labeled on the ipsilateral side arise from the pyramidal tract as it courses through the pontine nuclei. These axons descend through the pontine tegmentum as a diffusely organized corticotegmental tract and enter the ipsilateral superior cerebellar peduncle. Fewer cerebrocerebellar axons leave the pyramidal tract caudal to the pontine nuclei and project into the contralateral superior cerebellar peduncle. Cerebrocerebellar projections through the superior cerebellar peduncles terminate pri‐marily in the cerebellar nuclei, where they are localized in the interpositus nuclei and in immediately adjacent areas of the dentate and fastigial nuclei.More caudally, labeled axons exit from the pyramidal tract and take a superficial route around the ventrolateral brainstem into the inferior cerebellar peduncles bilaterally. These projections are more numerous contralaterally and are directed primarily to the internal granule cell layer of the posterolateral folia of the anterior lobe, the posteromedial simplex lobule, and the dorsal paramedian lobule.Horseradish peroxidase injections were made into the cerebellar posterior lobe and deep nuclei and the results from these cases showed that the cerebrocerebellar pathway originates from pyramidal neurons in layer V primarily in the coronal, the precoronal, and the anterior and posterior sigmoid gyri on both sides. In these gyri, many of the HRP‐positive neurons were found in clusters of two to five neurons, aligned in anterior‐posterior strips.The results from all experiments provide evidence about the ontogeny of cerebrocerebellar projections. Projections through the superior cerebellar peduncles generally develop at 6–8 postnatal days of age, whereas projections through the inferior cerebellar peduncles first are seen at 8–10 days postnatally. Cerebrocerebellar projections reach their maximum development in the second postnatal week but sharply decrease in density during the third postnatal week. No cerebrocerebellar projections were observed after the seventh postnatal week of development. Possible functional implications for this transient projection

ISSN:0092-7317    

DOI:10.1002/cne.902210209

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

年代:1983

数据来源: WILEY

摘要:

AbstractIn order to classify the presynaptic elements contacting the principle class of globus pallidus neurons, electron microscopic examination of serial sections made from a medially located large globus pallidus neuron, labeled with intracellular horseradish peroxidase, was undertaken. In addition, the use of labeled and light microscopically reconstructed material allowed us to quantitatively determine the distribution of each bouton type along the soma and dendrites. Six types of presynaptic terminals contacting the labeled cell have been recognized. Type 1 endings, the most numerous (84%), make symmetrical contacts on all portions of the cell, except spines, contain large pleomorphic, and a few large dense‐core vesicles. Type 2 endings are filled with small spherical‐to‐ellipsoidal synaptic vesicles. They make asymmetrical contacts only with higher‐order dendrites and account for 12% of synaptic contacts onto the labeled neuron. Type 3 endings are large, contain sparsely distributed large pleomorphic vesicles, and make two symmetrical synapses per bouton, one onto a spine head and the other onto the underlying dendritic shaft. They are infrequent (0.2%), being found only in association with dendritic spines. Type 4 endings contain large pleomorphic synaptic vesicles and no dense‐core vesicles. They make symmetrical contacts with the short primary dendrites. Type 5 endings contain a mixture of small clear pleomorphic vesicles and numerous large dense‐core vesicles. They contact only the cell body and the short primary dendrites, making up 20% of somatic synaptic contacts but less than 1% of contacts onto dendrites. Type 6 boutons contain oval and flattened synaptic vesicles and establish symmetrical contacts with higher‐order dendritic branches and

ISSN:0092-7317    

DOI:10.1002/cne.902210210

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

年代:1983

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902210201

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

年代:1983

数据来源: WILEY