摘要:

AbstractThe differentiation of an identified sensory neuron, the grasshopper wing hinge Stretch Receptor (SR), is examined throughout embryogenesis. The morphological features of the SR axon, as it finds its path from the peripheral cell body to the CNS, and the timing of this peripheral growth were determined by intracellular injection of Lucifer yellow. The course of growth of the SR axon within the CNS and the sequence of formation of the identified branches in its characteristic central arborization were investigated by silver intensification of cobalt‐stained axons. In addition, intracellular recording from the cell body of SR was used to determine the onset of electrical excitability and the characteristics of the somal action potential. A brief account of the differentiation of the closely associated wing hinge Chordotonal Organ is also given.During differentiation, the cell bodies of SR and the first wing hinge Chordotonal Organ neuron (CTN1) extend processes and migrate posteriorly along a peripheral epithelial ridge. The cell bodies migrate up to 150 m̈m with a group of undifferentiated cells to a specific site at the posterior edge of the segment.As the SR and CTN1cell bodies migrate, their trailing axons stretch across the epithelial ridge. These axons form the medial body wall nerve (1D2) that the axons of subsequent sensory neurons foll

ISSN:0092-7317    

DOI:10.1002/cne.902020103

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe Golgi Rapid and Kopsch techniques have been used to provide material for an examination of the internal neuronal organization of cortical area VII of theMacacamonkey. The afferent and efferent relationships of area VII, as shown by axoplasmic transport tracing techniques in our own material and in previous studies in other laboratories, are reviewed. Comparison is made between the internal organisation of VI and VII cortex in terms of (1) the marked difference in spiny and nonspiny neuron populations of granular layer 4, (2) the difference in relationship of lamina 6 pyramidal neurons to the overlying layers with a shift away from any relationship to granular layer 4 in VII, and (3) differences in the organization of VI lamina 4B and VII lamina 3B—both similarly placed, fiber‐rich bands in the two cortical areas. The extrinsic relationships of VI and VII with the lateral geniculate nucleus, superior colliculus, pulvinar, peristriate cortex, cortical area STS, and with each other are compared in terms of laminar locations of efferent neurons and afferent axon terminal fields. It is hoped that this anatomical survey will provide a better foundation for physiological explorations of the reg

ISSN:0092-7317    

DOI:10.1002/cne.902020104

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

年代:1981

数据来源: WILEY

摘要:

AbstractTo evaluate the contributions of the ear and acoustic stimulation to the structural development of central auditory neurons, the right otocyst was surgically destroyed in chick embryos on the third day of incubation. This pro‐cedure prevents the formation of the inner ear and acousticovestibular nerve and thus removes the dominant afferent synaptic input to nucleus magnocellularis (NM). Subsequently, nucleus laminaris (NL), which receives afferent synaptic input to its dorsal dendrites from the ipsilateral NM and afferents to its ventral dendrites from the contralateral NM, was studied on both sides of the brain in Golgi preparations. By embryonic day 17, the total lengths of the individual NL dendritic fields connected to the right NM (i.e., the manipulated dendrites) were decreased by an average of 44% as compared to those NL dendrites connected to the left NM (i.e., the unmanipulated dendrites). The mean length of the unman‐ipulated dendrites in experimental animals, however, did not differ from average dendritic length in normal control embryos. The amount of dendritic length lost by a NL neuron was strongly correlated with the length of the unmanipulated dendrites on the opposite side of the same neuron and with that neuron's position within NL. The lengths of dorsal and ventral dendrites on individual neurons were at least as highly correlated in experimental as in normal control animals. Correlation of dendrite length with the position of measured neurons within NL indicated that the large rostromedial‐to‐caudolateral gradient of increasing den‐drite length present in the normal NL is also found in the manipulated dendrites in experimental animals. Regression and correlation analyses relating the length of dendrites to their longitudinal cross‐sectional area revealed that there was no difference in mean dendritic diameter between the manipulated and unmani‐pulated dendrites in experimental animals. The findings of a high dorsal‐ventral length correlation in experimental animals and a normal spatial gradient of dendritic length among the manipulated dendrites suggests two explanations. Either (1) acoustically evoked synaptic activity is not essential for the develop‐ment of these two aspects of dendritic organization, or (2) the normal NM afferents to the unmanipulated dendrites of each NL neuron in an animal with one ablated otocyst can, under the influence of acoustically driven activity, control develop‐ment of the manipulated dendrites. These alternate hypotheses can be te

ISSN:0092-7317    

DOI:10.1002/cne.902020105

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe ascending projections to the major midbrain auditory center of anura, the torus semicircularis, have been examined using the technique of retrograde labeling with horseradish peroxidase (HRP). Localized iontophoretic injections of HRP were made in one torus semicircularis of Queensland cane toads(Bufo marinus). Visualization of HRP‐labeled neurons with tetramethyl benzidine revealed that the torus semicircularis receives its major afferent input from the ipsilateral superior olive. Other prominent projections arise in the contralateral dorsal nucleus of the eighth nerve and the contralateral torus semicircularis. HRP‐labeled neurons were also associated with the lateral lemniscus at a level ventral and lateral to the nucleus isthmi on both sides. It is suggested that these neurons constitute diffuse nuclei of the lateral lemnisci. Relatively minor projections to the torus semicircularis arise in the contralateral superior olive, ipsilateral dorsal nucleus of the eighth nerve, and the ventral division of both the ipsilateral and contralateral eighth nerve nuc

ISSN:0092-7317    

DOI:10.1002/cne.902020106

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe sensory representations in the tectum ofIguana iguanawere studied with electrophysiological recording techniques, and visual, somatic, and auditory cells were found to be represented here. These cells were not equally distributed throughout the tectal laminae. Upper tectal laminae were populated exclusively by visual cells, and deeper laminae were primarily nonvisual. The intermediate laminae had nonvisual, as well as visual, cells.Maps of the visual and somatic representations were constructed, and both representations were topographic and in register with one another. When electrical stimulation was presented via implanted electrodes, orientation responses were evoked that were predictable on the basis of the visuotopic and somatotopic maps.These organizational features of the iguana tectum are strikingly similar to those described in various mammalian species. It is suggested that the pattern of sensory and motor representation used in the midbrain of mammals is an ancient scheme that was retained during the transition from reptilian to mammalian forms more than 180 million years ago.

ISSN:0092-7317    

DOI:10.1002/cne.902020107

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe distribution of somatostatin (SRIF)‐immunoreactive structures in the central nervous system of the bull frog (both with and without treatment of colchicine) was studied, using the indirect immunofluorescence technique of Coons and co‐workers (Coons, '58). SRIF‐containing cells were observed in more than ten areas including the spinal cord. These SRIF‐positive cells showed segmental distribution, in that SRIF‐positive neurons were identified in various areas at various brain levels. An extensive network of SRIF‐positive fibers was found in most parts of the central nervous system. The distribution of a catecholamine (CA)‐containing neuron system in the frog brain is also presented in this study. The possible interactions between SRIF and CA neuron systems are brie

ISSN:0092-7317    

DOI:10.1002/cne.902020108

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe morphological organization of the somatostatin (SRIF)‐positive neurons in the forebrain (telencephalon and diencephalon) of the warbling grass parakeet(Melopsittacus undulatus)was studied using the indirect immunohistochemical technique of Coons and co‐workers ('58). In the telencephalon, a number of SRIF‐positive neurons was detected in the lobus paraolfactorius, hippocampus, and paleostriatum. Furthermore, scattered SRIF‐labeled cells were noticed in the area corticoidea dorsolateralis and area temporoparieto‐occipitalis. A moderate density of immunoreactive fibers was found in the above areas. In addition, although the septal area was devoid of SRIF‐positive neurons, this area contained a moderate number of SRIF‐positive fibers. A large number of SRIF‐positive neurons occurred in the following hypothalamic areas: (1) nucleus medialis hypothalami posterior, (2) lateral hypothalamus, and (3) mammillary nucleus. The bird hypothalamus also received a strikingly massive SRIF innervation. The heaviest concentration of SRIF‐labeled fibers was detected in the median eminence. Many SRIF‐labeled fibers were also observed in other hypothalamic regions. Their locations roughly corresponded in many cases to the areas in which SRIF‐positive neurons were disclosed.The overall distribution of the catecholamine system (CA) of the avian forebrain is also presented by means of histofluorescent technique. A possible interaction between SRIF and CA neuron systems

ISSN:0092-7317    

DOI:10.1002/cne.902020109

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

年代:1981

数据来源: WILEY

摘要:

AbstractWith the indirect immunofluorescence technique of Coon's and collaborators, overall distribution of the somatostatin (SRIF)‐positive neuron system in the avian lower brain stem was explored. Numerous cell somata containing SRIF were identified in the interpeduncular nucleus and substantia grisea centralis (GCT) at the level of the nucleus nervi trochlearis. Furthermore, a moderate number of SRIF‐positive neurons were seen in the tectum opticum, nucleus tractus solitarii, and spinal cord. Scattered labeled cells were noticed in the rhombencephalon. A dense network of SRIF‐positive fibers was distributed widely in the lower brain stem of birds. Their locations corresponded in many cases to the areas where SRIF‐positive neurons were found.The present study also presents the distribution of the catecholamine (CA) neuron system in the avian lower brain stem.Possible interactions between SRIF and CA neuron systems are briefly di

ISSN:0092-7317    

DOI:10.1002/cne.902020110

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe distribution of catecholamine (CA) in the inferior olivary complex (IO) of various vertebrate (from fish to monkey) was investigated by means of the histofluorescence technique. In addition, using rats, a further attempt was made to elucidate the origins of CA in the IO.The IO of the lower vertebrates (from fish to birds) was in general poorly innervated by the CA neuron system. IO in the lower mammals, such as insectivora and bats, contained only a few CA nerve terminals, while that in the higher mammals such as rat, guinea pig, rabbit, cat, and monkey revealed quite a number. In these animals, species‐specific patterns of CA nerve terminals were found. In the rat, the highest concentration was observed in the dorsal lamella of the principal nucleus and in the guinea pig ventral lamella. In the rabbit and cat, maximum CA nerve terminals were detected in the dorsal accessory nucleus, while in the monkey, they were detected in the medial accessory nucleus.The retrograde tracer technique of horseradish peroxidase (HRP) suggested that the main source of the abundant CA terminals in IO of the rat might be A1, A2, and A3noradrenaline neurons, though not locus coeruleus and not dopaminergic one

ISSN:0092-7317    

DOI:10.1002/cne.902020111

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

年代:1981

数据来源: WILEY

摘要:

AbstractA significant number of unmyelinated axons and their synaptic endings in the frog,Rana pipiens, were found to retain a normal morphology long after separation from their cell bodies. At the end of various survival periods following unilateral removal of the retina, horseradish peroxidase (HRP) was administered to the optic nerve stump by a fiber‐filling method. In frogs maintained at 20°C, unmyelinated optic nerve axons conducted HRP from the site of application in the orbit to layers A, C, and E of the contralateral optic tectum, even though their retinas had been removed up to 69 days earlier. Such fiberfilling was absent beyond 19 days in other frogs surviving at 35°C. No labeled fibers were continuous with any intracerebral neurons. The HRP was always localized intraaxonally, and the marked axons and terminals were ultrastructurally normal. Counts of surviving axons from electron micrographs of the optic nerves showed that, at 20°C, more than half of the normal complement of unmyelinated axons disappeared in the first 10 days. All the myelinated axons degenerated during the first 6 weeks survival. However, approximately 55,000 normal‐appearing unmyelinated axons (12% of the unmyelinated fiber population) persisted in the optic nerve at 10 weeks following removal of the retina. The survival rate was lower at 35°C.In other frogs, one eye was injected with3H‐leucine to initiate axonal transport into the retinal ganglion cell axons. That eye was removed 48 hours later. Autoradiographic analysis of brain sections of frogs surviving an additional 31 to 61 days at 20°C showed strong labeling of the optic tract and layers A, C, and E of the contralateral optic tectum. The absence of displaced ganglion cells that might exist within the optic nerve was verified by other observations.It is hypothesized that the potential shown by frog optic axons for long‐term survival in the absence of the cell‐body expresses a general property of vertebrate (and invertebrate) axons, rather than a special property of the fr

ISSN:0092-7317    

DOI:10.1002/cne.902020112

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

年代:1981

数据来源: WILEY