摘要:

AbstractThe projection regions of electroreceptor and mechanical lateral line afferents in electric fish of the mormyridae family are described.Electroreceptor afferents from the posterior dorsal skin run in the dorsal branch of the posterior lateral line nerve. Electroreceptor afferents from ventral skin and mechanical lateral line afferents and efferents run in the ventral branch of the nerve. Horseradish peroxidase (HRP) injections into each branch resulted in filling of its central terminals with the marker enzyme. The method yields a Golgi‐like staining of afferent terminals, allowing some aspects of their morphology to be described. Comparison of results from dorsal and ventral branch injections shows the separate medullary regions to which electroreceptor and mechanical afferents project, and also demonstrates four separate somatotopic maps within the electroreceptor region.Mechanical afferents end predominantly ipsilaterally in nucleus anterior and eminentia granularis as has been suggested by others. Ipsilateral endings in nucleus octavius are also seen. Electroreceptor afferents end exclusively in the cortex and nucleus of posterior lateral line lobe (PLLL). Within the cortex there are three distinct maps of the skin surface which are separated from each other by discontinuities in the cellular layers. Somatotopic mapping is also present in the nucleus of PLLL though it is less precise than in the cortical zones. Large club endings of the cells of this nucleus are filled with HRP. Labeled cells are seen within a small midline nucleus located at the level of the eighth nerve just above the medial longitudinal fasciculus. These are probably the cell bodies of lateral line efferent

ISSN:0092-7317    

DOI:10.1002/cne.901820302

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe subthalamic nucleus (ST) of kittens was studied by means of the rapid Golgi silver impregnation method.The neurons of the ST were classified into three types. Type I neurons, the main constituents of the ST, had oval or polygonal cell bodies with a mean diameter of 26 μm by 36 μm and four to six primary dendrites. Type II neurons had multipolar or polygonal cell bodies, which measured an average 31 μm by 43 μm and emitted four to seven primary dendrites. The cell bodies of the type III neurons were polygonal in shape, measured 23 μm by 26 μm in average and emitted four to six primary dendrites. The dendrite bundle and the dendrite pallisade were observed. Frequently dendrites of the ST extended into the cerebral peduncle (CP), and even cell bodies of some ST neurons were located within the CP. All of the parent axons of the ST neurons coursed rostrally, although intra‐ and extra‐nuclear axon‐collaterals arising from the ST neurons travelled rostrally, caudally or caudomedially.The afferent fibers to the ST were divided into three groups; afferents via the Meynert's commissure (MC), descending and ascending afferents. The MC fibers, which ran across the CP, gave terminals to the ST. The descending afferents were axon‐collaterals of fibers descending in the CP and those of fibers running through the ST. The ascending afferents were also axon‐collaterals arising from ascending fibers in the CP. In addition to these afferents, many descending and ascending fibers of passage ran through the ST without emitting a

ISSN:0092-7317    

DOI:10.1002/cne.901820303

出版商:The Wistar Institute of Anatomy and Biology    

年代:1978

数据来源: WILEY

摘要:

AbstractWe have assessed the effects of 15 pigmentation mutations on the development of retinal ganglion cell projections in mice in two ways: (1) by analyzing the pattern of innervation of the ipsilateral lateral geniculate nucleus as mapped in autoradiograms of brains of animals killed 12 days after intravitreal injection of3H‐proline into one eye and (2) by determining the ratio of axonally transported radioactive protein in the contralateral and ipsilateral optic tracts after similar intravitreal injections. Analysis of the ratio of transported protein in the two optic tracts provides a new and useful assay of the degree of decussation in experimental animals. The effects of the mutations on eye pigmentation, whole eye melanin content and relative tyrosinase activity also were examined. The degree of ipsilateral innervation generally correlates with the degree of pigmentation of the retinal pigment epithelium and with tyrosinase activity. However, discrepancies have been found in chand cemutants. In these animals the pigment epithelium is well pigmented, and the area of ipsilateral innervation in the lateral geniculate nucleus is extensive, despite a high ratio of label in contralateral to ipsilateral optic tracts and low tyrosinase activity. Furthermore, mice heterozygous for the c2Jallele have pigmentation and optic projections that are normal even though tyrosinase is reduced to 40% of normal. The few anomalous results suggest that alternative or additional factors may control optic axon projection

ISSN:0092-7317    

DOI:10.1002/cne.901820304

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

年代:1978

数据来源: WILEY

摘要:

AbstractIn this study of the medial geniculate body in the tree shrew eight subdivisions are identified on the basis of differences recognized in Nissl‐stained material. Experiments using the methods of anterograde and retrograde axonal transport and anterograde degeneration show that each subdivision has a unique pattern of connections with the midbrain.The ventral division of the medial geniculate body contains at least two subdivisions, the ventral nucleus and the caudomarginal nucleus. The ventral nucleus is characterized by densely‐packed cells and receives topographically organized projections from the central nucleus of the inferior colliculus. The caudomarginal nucleus, on the other hand, receives its major midbrain projections from the medial nucleus in the inferior colliculus.In the dorsal division four subdivisions are distinguished. The suprageniculate nucleus contains large, loosely‐packed cells and receives projections from the deep layers of the superior colliculus and from the midbrain tegmentum. The dorsal nucleus receives projections from the midbrain tegmentum. The deep dorsal and anterodorsal nuclei have neurons which resemble those in the dorsal nucleus. Both receive projections from the roof nucleus of the inferior colliculus but the deep dorsal nucleus receives an additional projection from the parabrachial tegmentum.The medial division has a rostral and a caudal subdivision. The ascending projections to the rostral nucleus are from the lateral zone in the inferior colliculus and from the spinal cord. The caudal nucleus contains cells with large somas and receives projections from most of the midbrain areas which project to the other subdivisions of the medial geniculate

ISSN:0092-7317    

DOI:10.1002/cne.901820305

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

年代:1978

数据来源: WILEY

摘要:

AbstractIn this study the temporal cortex of the tree shrew was subdivided on the basis of cytoarchitectonic criteria, and the connections of each subdivision with the thalamus and midbrain were analyzed with retrograde and anterograde techniques.The results indicate that, with one exception, each subdivision of the medial geniculate body projects to a separate cortical area. The primary auditory cortex receives projections from the ventral nucleus. Surrounding the primary cortex are at least five additional cytoarchitectonically distinct areas which receive projections from the remaining medial geniculate subdivisions. The evidence suggests that there is very little overlap in the projections from each of these geniculate subdivisions. An exception is the projection of the caudal nucleus of the medial division. This subdivision apparently projects to most, if not all, of the cortical target of the medial geniculate body. Although the cortical projections of the caudal nucleus overlap those of the other medial geniculate subdivisions, the laminar distribution of its terminationsin cortex is different. The caudal nucleus projects primarily to layer VI whereas the other subdivisions of the medial geniculate body project primarily to layer IV and the adjacent part of layer III.Anterograde techniques were also used to study the projections from the cortex back to the thalamus and to the midbrain. The projections to the thalamus precisely reciprocate the thalamocortical connections. The projections to the midbrain are to the same areas which the preceding study (Oliver and Hall, '78) showed give rise to ascending projections to the medial geniculate body. An exception is the central nucleus of the inferior colliculus which apparently does not receive a projection from the temporal cortex.

ISSN:0092-7317    

DOI:10.1002/cne.901820306

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe morphological organization of the monoamine‐containing neurons in the brain of the sunfish (Lepomis gibbosus) was studied by means of the Falck‐Hillarp histofluorescence method. No attempt was made to distinguish between norepinephrine and dopamine, both primary catecholamines (CA) yielding a similar yellow‐green fluorescence after paraformaldehyde treatment. In the brain stem of this teleost fish, three groups of CA‐containing neuronal somata have been found. First, there is a small collection of CA perikarya located just caudal to the obex of the fourth ventricle. The neurons of thismedullo‐spinal groupgive rise to numerous CA fibers many of which ascend within the central portion of the medulla. Intermingled with these CA fibers are some CA cells that constitute thecentral medullary group. The CA perikarya of this group are scattered between the levels of cranial nerves X and VIII. The tegmentum of the isthmus also contains a small group of very closely packed CA neurons. The large‐sized CA cells of theisthmal groupare located dorsolateral to the medial longitudinal fasciculus, partly within the periventricular gray. High densities of CA varicosities were also disclosed in various brain stem structures such as the optic tectum, the torus semicircularis and the cerebellar valvula. In addition, numerous serotonin (5‐HT)‐type neuronal somata were found in theraphe regionof the brain stem, particularly at caudal mesencephalic, isthmal and rostral medullar levels.A large number of CA cell bodies were visualized in the sunfish hypothalamus. Most of them form two populations of small, round cells that are located along and partly within the ependymal walls of theposterior and lateral recessesof the third ventricle. These bipolar cells possess one short club‐like process protruding into the ventricle and their thin ependymofugal processes contribute to the CA innervation of numerous hypothalamic regions. Large CA neurons apparently without direct CSF contact also occur in the area ofnucleus posterior tuberis, at the level of the mesodiencephalic junction. Although the hypothalamic inferior lobes are devoid of CA cell bodies they are heavily innervated by CA axons.The sunfish telencephalon also receives a strikingly massive and complex monoaminergic innervation. Numerous CA fibers which are first observed at the level of the preoptic area, ascend through the central zone of the telencephalon and arborize profusely particularly within the medial zone of area dorsalis telencephali. Other CA fibers, as well as abundant fine 5‐HT varicosities were found in the lateral zone of area dorsalis. Although the exact origin of the telencephalic CA afferents inLepomisis not known, part of it may arise from the isthmal CA cell group which appears similar to the locus coeruleus of reptiles

ISSN:0092-7317    

DOI:10.1002/cne.901820307

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

年代:1978

数据来源: WILEY

摘要:

AbstractAutoradiographic tracing procedures have been used to study the organization of retinogeniculate axons in seven primates, i.e., four species of New World monkeys, one species of Old World monkeys and two species of prosimians. These data suggest that the basic primated pattern of geniculate lamination consists of two parvocellular layers, two magnocellular layers, and two poorly developed and highly variable superficial (S) layers which are ventrally lacoted. Ocular input to each member of each of the three pairs differs. In the macaque, the squirrel, and the saki monkey, the parvocellular layers subdivide and interdigitate into four leaflets so as to give the appearance of four parvocellular “layers”. These leaflets are much less extensive in the owl and marmoset monkeys. In some individual macaque monkeys, there is further splitting of the parvocellular leaflets into subleaflets, giving the appearance of six parvocellular “layers”. The prosimians (galago and slow loris) have two additional layers that are not found in pithecoid primates, and only one superficial layer is apparent. The two additional layers are termed “koniocellular” since they consist of very small cells. Finally, New and Old World monkeys have both ipsilateral and contralateral retinal input to the interlaminar zones.We conclude that the basic pattern of lateral geniculate organization is six layers, but not the traditional six. Prosimians have evolved two additional layers, the koniocellular layers, and have possibly lost one superficial layer. Both New World and Old World monkeys have elaborated the parvocellular layers by forming leaflets to varying extents. With the possible exception of the single S layer in prosimians, layers form pairs that are similar in cell types, but different in o

ISSN:0092-7317    

DOI:10.1002/cne.901820308

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe ascending connections to the striatum and the cortex of the Tegu lizard,Tupinambis Nigropunctatus, were studied by means of anterograde fiber degeneration and retrograde axonal transport. The striatum receives projections by way of the dorsal peduncle of the lateral forebrain bundle from four dorsal thalamic nuclei: nucleus rotundus, nucleus reuniens, the posterior part of the dorsal lateral geniculate nucleus and nucleus dorsomedialis. The former three nuclei project to circumscribed areas of the dorsal striatum, whereas nucleus dorsomedialis has a distribution to the whole dorsal striatum. Other sources of origin to the striatum are the mesencephalic reticular formation, substantia nigra and nucleus cerebelli lateralis. With the exception of the latter afferentation all these projections are ipsilateral.The ascending connections to the pallium originate for the major part from nucleus dorsolateralis anterior of the dorsal thalamus. The fibers course in both the medial forebrain bundle and the dorsal peduncle of the lateral forebrain bundle and terminate ipsilaterally in the middle of the molecular layer of the small‐celled part of the mediodorsal cortex and bilaterally above the intermediate region of the dorsal cortex. The latter area is reached also by fibers from the septal area. The large‐celled part of the mediodorsal cortex receives projections from nucleus raphes superior and the corpus mammill

ISSN:0092-7317    

DOI:10.1002/cne.901820309

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

年代:1978

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901820301

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

年代:1978

数据来源: WILEY