摘要:

AbstractOmnipause neurons take part in the generation of saccadic eye movements. They lie around the midline in the caudal pontine reticulur formation, in an area usually ascribed to the nucleus raphe pontis (rp). In this study of the monkey (Macaca fascicularisandM. mulatta), we describe four series of experiments aimed at establishing that omnipause neurons lie within a distinctive cytoarchitectonic entity, which we call the nucleus raphe interpositus (rip): (1) cytoarchitectural study, (2) recording‐lesion experiments to establish in which cell group omnipause neurons lie, (3) cytochrome oxidase distribution in the omnipause region and neighboring structures, and (4) neuroanatomical tracing experiments to demonstrate afferents to the omnipause region.In the detailed cytoarchitectural study of the midline structures in the caudal pons and rostral medulla, a distinctive group of neurons (rip) adjoining the ventrocaudal border of rp and dorsal to the nucleus raphe magnus (rm) is described. The striking features of rip are the uniformly arranged, narrow row of the cells either side of the midline, and the extensive horizontally oriented dendritic trees of its neurons. The abducens rootlets (NVI) pass through the reticular formation at the same rostrocaudal level as rip and form a reliable landmark for its location. Cytochrome‐oxidase‐stained sections demonstrated additional differences between rip and adjacent cell groups: in rip the neurons and their extensive dendrites stained strongly, but not the surrounding neuropile, whereas in rp both the neurons and the neuropile stained darkly, so that individual neurons were difficult to see.Unlike rp, rip coincides with the location of omnipause neurons, and lesions marking the sites of individual omnipause units lay within its boundaries. Tritiated leucine was injected into superior colliculus (sc), which is known to have monosynaptic connections with omnipause neurons. Labelled axons and patterns of silver grains taken to indicate the presence of terminal branching were found in and around rip, but no significant labelling was seen in rp or rm. It is concluded that the omnipause neurons lie within the rip in the monkey.These functional and morphological differences between rip and the adjacent raphe nuclei are used to justify its characterization as an independent cell group in the monkey.In order to relate these findings to man, cytochrome oxidase experiments were carried out to the human brainstem, and the pattern of staining at the level of the abducens rootlets was correlated with the cytoarchitecture. Similar results to those in the monkey were found, and a group of cells is outlined which we suggest is the homologue of rip i

ISSN:0092-7317    

DOI:10.1002/cne.902670302

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe tritiated amino acid autoradiographic method was employed to characterize the patterns of commissural projections originating in the hippocampus of the rat, guinea pig, rabbit, and cat. The results demonstrate that significant differences between species are present despite the overall similarity of the projections. In the rat and cat the commissural connections are widely distributed along the septotemporal axis of the hippocampus, but in the guinea pig and rabbit they are less widely distributed along this axis. Second, within the hippocampus proper the radial distribution of the commissural projection is species specific. In the rat, CA3commissural projections are present in both the strata oriens and radiatum, but the densest projection is to the stratum oriens. In the guinea pig the radial distribution of this projection is similar to that observed in the rat, but in the rabbit the projection is almost entirely confined to the stratum oriens. In contrast, in the cat the CA3commissural projection is very dense to the stratum radiatum and sparse to stratum oriens. An analysis of the relative density of label in the molecular layer of the fascia dentata suggests that the density of the commissural projection from CA4is much greater in the rat and cat than in the guinea pig or rabbit. These results indicate that care must be exercised in the generalization of connectional data between species. The results also suggest a possible explanation for differences observed in the electrophysiology of these connections between species.

ISSN:0092-7317    

DOI:10.1002/cne.902670303

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

年代:1988

数据来源: WILEY

摘要:

AbstractSensory neuronal cell bodies in the leg of locust,Schistocerca gregaria, were visualized with antibodies to locust choline acetyltransferase and with antibodies to serotonin by the avidin‐biotin peroxidase technique. Two groups of sensory cells react with the antibody to choline acetyltransferase: One group is associated with external mechanoreceptors (i.e., hair‐plate hairs and campaniform sensilla) and the other with internal proprioceptors (i.e., chordotonal organs and multiterminal receptors). Sensory cells which react with the antibody to serotonin are associated only with internal proprioceptors being found in both chordotonal organs and multiterminal receptors. In the metathoracic femoral chordotonal organ indirect evidence suggests that some sensory cells are reactive to both antibodies. Some multiterminal receptors react with anti‐choline‐acetyltransferase, while others react with antiserotonin. These results support the conclusion that most insect sensory neurones are cholinergic but some are seroton

ISSN:0092-7317    

DOI:10.1002/cne.902670304

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

年代:1988

数据来源: WILEY

摘要:

AbstractWith antisera to gastrin/cholecystokinin, we studied the postembryonic development of neurons in the thoracic ganglia of the blowflyCalliphora erythrocephala.There are some changes in the population of thoracico‐abdominal neurons displaying gastrin/CCK‐like immunoreactivity (CCKLI): some CCKLI neurons cannot be found after pupariation; other neurons become immunoreactive during metamorphosis. Six large thoracic CCKLI neurons could, however, be followed through metamorphosis. These CCKLI neurons innervate neuropil in thoracic ganglia and segmental neurohemal organs in the larva. In the adult insect the same neurons innervate many regions of thoracic neuropil and extensive neurohemal areas dorsally in the fused thoracico‐abdominal ganglia. The immunoreactive terminals are located in the neural sheath, and electron microscopy shows that only an extracellular basal lamina separates them from the circulating hemolymph. On the basis of the location of their terminals, it can be suggested that the six CCKLI neurons have functions as neurosecretory cells both in the larva and in the adult. In both developmental stages the neurons can interact with large portions of the thoracic nervous system and release bioactive substance into the circulation. A CCK‐like substance may be used both as a transmitter/neuromodulator and as a neurohormone by the same neuron. The larval neurohemal organs are described here for the first time. They show characteristics of thoracic perisympathetic organs known to exist in more primitive insects. The adult neurohemal regions on the other hand are typical of higher insects. Since the neurohemal areas are continuously (during development) innervated by the six large CCKLI neurons, we conclude that the larval neurohemal organs metamorphose into the adult neurohemal area in the neural

ISSN:0092-7317    

DOI:10.1002/cne.902670305

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe dispositions of galactosyl‐containing glycoconjugates were studied during postnatal development of the caudate putamen in mice. The binding of the lectin peanut agglutinin, which has an affinity for galactosyl B‐1,3 N‐acetylgalactosamine residues, was compared to acetylcholinesterase staining and tyrosine hydroxylase immunoreactivity in the immature and adult neostriatum.The binding of peanut agglutinin conjugated to horseradish peroxidase, in sections that were processed for peroxidase histochemistry, was extremely pronounced in the neostriatum through the first postnatal week and constituted ringlike or polygonally shaped structures, which, overall, produced a variegated mosaic, These structures consist of outer rims of dense lectin‐associated reaction product surrounding lightly labeled centers. Lectin delineations of the neostriatal mosaic are no longer visible in the second postnatal week. When adjacent sections were processed for lectin binding or acetylcholinesterase histochemistry, the dense lectin binding sites represented borders of acetylcholinesterase‐rich and ‐poor zones. The distribution of dense patches of tyrosine hydroxylase immunoreactive fibers and terminals also coincides with the acetylcholinesterase‐rich zones during the same times, and thus the glycoconjugate‐delineated boundaries can also be directly compared with the distribution of nigrostriatal dopaminergic projections.The findings presented here represent the first demonstration of a probe that recognizes apparent borders of neostriatal compartments during a limited period of development. They are consistent with previous observations made on transient glycoconjugate “hidden boundaries” during development of other central nervous system structures, including the somatosensory cortical barrel field, and thalamic and brainstem nuclei (Cooper and Steindler, '86a, b; Steindler and Cooper, in press). In those studies, glia were shown to be the major source of glycoconjugate‐associated patterns, and thus, glia and glycoconjugates that they synthesize during pattern formation events may be involved in the formation and stabilization of neurochemically distinct components of t

ISSN:0092-7317    

DOI:10.1002/cne.902670306

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe motor nuclei of the oculomotor, trochlear, and abducens nerves of the reptileVaranus exanthematicusand the neurons that subserve the sensory innervation of the extraocular muscles were identified and localized by retrograde and anterograde transport of horseradish peroxidase (HRP). The highly differentiated oculomotor nuclear complex, located dorsomedially in the tegmentum of the midbrain, consists of the accessory oculomotor nucleus and the dorsomedial, dorsolateral, intermediate, and ventral subnuclei. The accessory oculomotor nucleus projects ipsilaterally to the ciliary ganglion. The dorsomedial, dorsolateral, and intermediate subnuclei distribute their axons to the ipsilateral orbit, whereas the ventral subnucleus, which innervates the superior rectus muscle, has a bilateral, though predominantly contralateral projection.The trochlear nucleus, which rostrally overlaps the oculomotor nuclear complex, is for the greater part a comma‐shaped cell group situated lateral, dorsal, and medial to the medial longitudinal fasciculus. Following HRP application to the trochlear nerve, almost all retrogradely labeled cells were found in the contralateral nucleus. The nuclear complex of the abducens nerve consists of the principal and accessory abducens nuclei, both of which project ipsilaterally. The principal abducens nucleus is located just beneath the fourth ventricle laterally adjacent to the medial longitudinal fasciculus and innervates the posterior rectus muscle. The accessory abducens nucleus has a ventrolateral position in the brainstem in close approximation to the ophthalmic fibers of the descending trigeminal tract. It innervates the retractor bulbi and bursalis muscles. The fibers arising in the accessory abducens muscles form a loop in or just beneath the principal abducens nucleus before they join the abducens nerve root.The afferent fibers conveying sensory information from the extraocular muscles course in the oculomotor nerve and have their perikarya in the ipsilateral trigeminal ganglion, almost exclusively in its ophthalmic portio

ISSN:0092-7317    

DOI:10.1002/cne.902670307

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

年代:1988

数据来源: WILEY

摘要:

AbstractWe studied the anatomical pathway underlying the nictitating reflex in the monitor lizardVaranus exanthematicusby the anterograde degeneration technique combined with retrograde transport of horseradish peroxidase (HRP) and electron microscopy.After application of HRP to the abducens nerve, retrogradely labeled neurons were observed in the ipsilateral principal and accessory abducens motor nuclei. The transection, in the same experiments, of the root of the trigeminal nerve resulted in massive degeneration of myelinated fibers in the descending trigeminal tract. In the ipsilateral accessory abducens nucleus, we observed electron‐dense degenerating axon terminals that formed asymmetric synaptic contacts with the primary and secondary dendrites of large neurons retrogradely labeled with HRP. A few of the degenerating terminals could be traced in serial sections to myelinated axons. No terminal degeneration was found in the contralateral accessory abducens nucleus or in the ipsilateral and contralateral principal abducens nuclei. The present results are complementary with the findings of previous light microscopic experimental tracing studies (Barbas‐Henry, H.A., and A.H.M. Lohman, J. Comp. Neurol. 1986,254:314–329; see also J. Comp. Neurol. 1988,267:370–386), and strongly suggest the existence in Varanus of a monosynaptic, unilateral reflex pathway in which trigeminal fibers, presumably originating from the cornea, synapse with motoneurons of the bursalis and retractor bulbi muscles, which are located in the accessory abducens nucleus. This monosynaptic pathway may mediate a rapid unilateral eyeball retraction and nictitating membrane ex

ISSN:0092-7317    

DOI:10.1002/cne.902670308

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

年代:1988

数据来源: WILEY

摘要:

AbstractMonoclonal antibody probes were used to identify antigenic cross reactivities among neuronal subpopulations and to dissect the human nervous system at several levels of organization. Six monoclonal antibodies, prepared with immunogens fromDrosophila melanogasteror human nervous tissue, were used to localize antigens immunocytochemically in normal adult human neocortex, hippocampus, cerebellum, spinal cord, and retina. Four of the six antibodies were neural specific in their reactivity and each stained a unique combination of neurons. The antibodies reacted with at least three subpopulations of cerebral cortical neurons, including discrete populations of pyramidal and nonpyramidal cells. Components of a widely distributed functional system within the spinal cord and cerebellum were labelled by one antibody, which reacted with neurons in the nucleus dorsalis of Clarke, deep cerebellar nuclei, and Purkinje cells. At the single‐cell level, three of the monoclonals differentially labelled the photoreceptor cell outer segment, inner segment, and perikaryon. Three of the six antibodies were reactive with specific protein bands, on immunoblots of tissue homogenates. This monoclonal antibody panel provides a novel and potentially useful method of analysis of the organization of the normal and diseased human nervous syste

ISSN:0092-7317    

DOI:10.1002/cne.902670309

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

年代:1988

数据来源: WILEY

摘要:

AbstractOur earlier Golgi‐electron microscopic study of bipolar cells in the rat visual cortex showed the axons of these neurons as forming asymmetric synapses (Peters and Kimerer;J. Neurocytol, 10:921–946, '81) in which the most common postsynaptic elements were dendritic spines. This result was unexpected, since Parnavelas (Parnavelas, Sullivan, Lieberman, and Webster:Cell Tissue Res.183:499–517, '77) had earlier shown a bipolar cell from the same cortex to have an axon forming symmetric synapses with dendritic shafts. Here then was an enigma, strengthened by examination of neuronal components labelled by antibodies to two compounds in particular—namely, vasoactive intestinal polypeptide (VIP) and choline acetyltransferase (ChAT). Antibodies to these compounds preferentially label bipolar cells in the rat cerebral cortex, and the labelled axon terminals form symmetric synapses.Against this background the present study was performed, and it has been shown that the resolution to the enigma is that there are two different populations of bipolar cells in the rat visual cortex. Thus some Golgi‐impregnated bipolar cells examined by electron microscopy after gold toning have been found to possess axons forming asymmetric synapses, and others have been found to have axons forming symmetric synapses, The axons of the bipolar cells forming asymmetric synapses most commonly synapse with dendritic spines (67%), although other terminals synapse with dendritic shafts (33%). In contrast, the bipolar cells with axons forming symmetric synapses preferentially synapse with dendritic shafts (100%). The population of bipolar cells that form symmetric synapses includes the ones that label with antibodies to vasoactive intestinal polypeptide (VIP), for the axons of VIP‐labelled bipolar cells have been traced to labelled terminals forming symmetric synapses. However, examination of the population of VIP‐labelled axon terminals shows that in addition to dendritic shafts, some of the labelled terminals synapse with the cell bodies of pyramidal and nonpyramidal cells, This includes bipolar cells, some of which receive large numbers of VIP‐labelled axon terminals. It is also shown that some VIP‐positive bipolar cells have myelinated axons. Analysis of tissue labelled with VIP antibody reveals that about 50% of the total population of bipolar cells in the rat visual cortex is VIP positive. These results are discussed in the light of information about labelling of bipolar cells with antibodies to γ‐aminobutyric acid (GABA) and to other peptides, and it is suggested that most VIP‐positive bipolar c

ISSN:0092-7317    

DOI:10.1002/cne.902670310

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

年代:1988

数据来源: WILEY

摘要:

AbstractBrainstem afferents to the magnocellular basal forebrain were studied by using tract tracing, immunohistochemistry and extracellular recordings in the rat. WGA‐HRP injections into the horizontal limb of the diagonal band (HDB) and the magnocellular preoptic area (MgPA) retrogradely labelled many neurons in the pedunculopontine and laterodorsal tegmental nuclei, dorsal raphe nucleus, and ventral tegmental area. Areas with moderate numbers of retrogradely labelled neurons included the median raphe nucleus, and area lateral to the medial longitudinal fasciculus in the pons, the locus ceruleus, and the medial parabrachial nucleus. A few labelled neurons were seen in the substantia nigra pars compacta, mesencephalic and pontine reticular formation, a midline area in the pontine central gray, lateral parabrachial nucleus, raphe magnus, prepositus hypoglossal nucleus, nucleus of the solitary tract, and ventrolateral medulla. A similar but not identical distribution of labelled neurons was seen following WGA‐HRP injections into the nucleus basalis magnocellularis.The possible neurotransmitter content of some of these afferents to the HDB/MgPA was examined by combining retrograde Fluoro‐Gold labelling and immunofluorescence. In the mesopontine tegmentum, many retrogradely labelled neurons were immunoreactive for choline acetyltransferase. In the dorsal raphe nucleus, some retrogradely labelled neurons were positive for serotonin and some for tyrosine hydroxylase (TH); however, the majority of retrogradely labelled neurons in this region were not immunoreactive for either marker. The ventral tegmental area, substantia nigra pars compacta, and locus ceruleus contained retrogradely labelled neurons which were also immunoreactive for TH. Of the retrogradely labelled neurons occasionally observed in the nucleus of the solitary tract, prepositus hypoglossal nucleus, and ventrolateral medulla, some were immunoreactive for either TH or phenylethanolamine‐N‐methyltransferase.To characterize functionally some of these brainstem afferents, extracellular recordings were made from antidromically identified cortically projecting neurons, mostly located in the HDB and MgPA. In agreement with most previous studies, about half (48%) of these neurons were spontaneously active. Electrical stimulation in the vicinity of the pedunculopontine tegmerital and dorsal raphe nuclei elicited either excitatory or inhibitory responses in 21% (13/62) of the cortically projecting neurons.These findings indicate that neurons in the magnocellular basal fore‐brain receive afferents from widely distributed brainstem neurons that contain acetylcholine, serotonin, dopamine, noradrenaline, adrenaline, and some unknown neurotransmitters. Through their actions on magnocellular basal forebrain neurons, these brainstem neurons may indirectly regulate the activity of neurons throughout the cere

ISSN:0092-7317    

DOI:10.1002/cne.902670311

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

年代:1988

数据来源: WILEY