摘要:

AbstractRecent works utilizing glycine‐immunoreactivity (IR) and combined Golgi impregnation and3H‐glycine uptake autoradiography indicate that glycinergic interplexiform cells (IPC) may synapse upon cell bodies in the inner nuclear and ganglion cell layers in fish retina. This possibility was investigated with immunocytochemical techniques using presynaptic and postsynaptic markers for glycinergic neurons: a monoclonal antibody (mAb 7A) against the 93 kDa subunit of the strychnine‐sensitive glycine receptor and a polyclonal antiserum against a glycine/BSA conjugate. Synaptic contacts onto the lateral and proximal surfaces of amacrine cell bodies and onto the distal surface of cells in the ganglion cell layer were identified with both probes. The contacts were rare with one contacted amacrine cell/section of 500 linear μm. Serial 1‐μm sections were processed alternately for glycine and GABA antisera using postembedding techniques at the light microscopic level. Glycine‐IR processes + boutons were apposed to GABA‐IR cell bodies in 16 of 17 examples, indicating that the dendro‐somatic contacts were onto GABA‐immunoreactive amacrine cell bodies. In context of other published morphological data, we suggest that the dendro‐somatic synapses were derived from glycinergic IPCs. Glycinergic IPCs receive input from GABAergic horizontal cells and, via a shunt conductance produced by the dendro‐somatic contacts, may be involved in controlling the sensitivity, temporal, or spatial properties of amacrine cell responses to la

ISSN:0092-7317    

DOI:10.1002/cne.903100103

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

年代:1991

数据来源: WILEY

摘要:

AbstractGlycinergic innervation of the synaptic terminals of mixed rod‐cone bipolar cells in the goldfish retina was investigated by electron microscopical immunocytochemistry with presynaptic and postsynaptic markers for glycinergic neurons: a monoclonal antibody (mAb 7A) against the 93 kDa subunit of the strychnine‐sensitive glycine receptor and polyclonal antisera against a glycine/BSA conjugate. Conventional “glycinergic” synaptic contacts, made by amacrine cell processes, accounted for 7–10% of the input to the bipolar cell terminals, whether determined by glycine receptor immunoreactivity (GlyR‐IR) or glycine‐IR. In addition to the conventional synapses, the large bipolar cell terminals in the proximal inner plexiform layer (type Mb) gave rise to spinules (spine‐like protrusions) that invaginated into presynaptic amacrine cell processes. Although 85% of the spinules were GlyR‐IR, no spinules were postsynaptic to glycine‐IR processes; yet 86% of the spinules were postsynaptic to GAD‐IR processes, suggesting that the GlyR‐IR spinules were postsynaptic to GABAergic terminals. Furthermore, a single amacrine cell process could make two synapses with an Mb terminal: a GlyR‐IR contact onto a spinule and a conventional synapse that wasnotGlyR‐IR. We suggest that glycinergic innervation of bipolar cell terminals involves conventional glycinergic synapses as well as an unconventional situation in which GABA and glycine may interact in as yet undetermined man

ISSN:0092-7317    

DOI:10.1002/cne.903100104

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe localization of calretinin in the rat hindbrain was examined immunohistochemically with an antiserum against calretinin purified from the guinea pig brain. Calretinin immunoreactivity was found within neuronal elements. The distribution of calretinin‐immunoreactive cell bodies and fibers is presented in schematic drawings and summarized in a table. Major calretinin immunoreactive neurons were found in the lateral and medial geniculate nuclei, substantia nigra, ventral tegmental area, interpeduncular nucleus, periaqueductal gray, mesencephalic trigeminal nucleus, superior and inferior colliculi, pontine nuclei, parabrachial nucleus, dorsal and laterodorsal tegmental nuclei, cochlear nuclei, vestibular nuclei, medullary reticular nuclei, nucleus of the solitary tract, area postrema, substantia gelatinosa of the spinal trigeminal nucleus, and cerebellum. These results show that distinct calretinin‐immunoreactive neurons are widely distributed in the rat hindb

ISSN:0092-7317    

DOI:10.1002/cne.903100105

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe immunocytochemical distribution of galanin‐containing perikarya and nerve terminals in the brain ofRana esculentaandXenopus laeviswas determined with antisera directed toward either porcine or rat galanin. The pattern of galanin‐like immunoreactivity appeared to be identical with antisera directed toward either target antige.The distribution of galanin‐like immunoreactivity was similar inRana esculentaandXenopus laevisexcept for the absence of a distinct laminar distribution of immunoreactivity in the optic tectum ofXenopus laevis.Galanin‐containing perikarya were located in all major subdivisions of the brain except the metencephalon. In the telencephalon, immunoreactive perikarya were detected in thepars medialisof the amygdala and the preoptic area. In the diencephalon, immunoreactive perikarya were detected in the caudal half of the suprachiasmatic nucleus, the nucleus of the periventricular organ, the ventral hypothalamus, and the median eminence. In the mesencephalon, immunoreactive perikarya were detected near the midline of the rostroventral tegmentum, in the torus semicircularis and, occasionally, in lamina A and layer 6 of the optic tectum. In the myelencephalon, labelled perikarya were detected only in the caudal half of the nucleus of the solitary tract. Immunoreactive nerve fibers of varying density were observed in all subdivisions of the brain with the densest accumulations of fibers occurring in thepars lateralisof the amygdala and the preoptic area. Dense accumulations of nerve fibers were also found in the lateral septum, the medial forebrain bundle, the periventricular region of the diencephalon, the ventral hypothalamus, the median eminence, the mesencephalic central gray, the laminar nucleus of the torus semicircularis, several laminae of the optic tectum, the interpeduncular nucleus, the isthmic nucleus, the central gray of the rhombencephalon, and the dorsolateral caudal medull.The extensive system of galanin‐containing perikarya and nerve fibers in the brain of representatives of two families of anurans showed many similarities to the distribution of galanin‐containing perikarya and nerve fibers previously described for the mam

ISSN:0092-7317    

DOI:10.1002/cne.903100106

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

年代:1991

数据来源: WILEY

摘要:

AbstractMigration and early differentiation of neurons of the tangential vestibular nucleus of the chick take place between embryonic days 5 and 8. In the absence of primary vestibular afferents (otocyst‐ablation), a previous light microscope study documented that early developmental events still occurred, but the neurons failed to complete differentiation and to survive. In order to understand why these neurons undergo normal early development, we have repeated the vestibular deafferentation paradigm followed by ultrastructural observations on these neuron.We found that the ultrastructural events associated with migration and differentiation in the deafferented tangential nucleus were essentially normal from 5 to 8 days. Most important, longitudinal fibers, presumably of central, nonvestibular origins, formed the first synapses at the same time and sequence as observed in normal embryos. Thus vestibular sensory neurons receive their first input from central fibers, initiating events in the formation of a central vestibular circuitry without the influence of peripheral vestibular fibers or endorg

ISSN:0092-7317    

DOI:10.1002/cne.903100107

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe tangential nucleus is a primary vestibular nucleus located where the vestibular fibers enter the medulla. It is composed of neurons that migrate between 5 and 8 days in the chick embryo. Although primary vestibular fibers enter the medulla at 3 days, the first synapses are formed at 5 days on the processes of neuron precursors by longitudinally coursing fibers. Since the major components, or their precursors, are present at 3 days within the presumptive nucleus, we are interested in determining what cellular interactions occur among these structures following their entry and during the time leading up to synapse formatio.At 2 days, prior to the appearance of VIIth and VIIIth nerve fibers in the medulla, the tangential nucleus anlage contained processes and endfeet of primitive epithelial cells, separated from each other by enlarged extracellular spaces. Longitudinal fibers first appeared within these spaces coincident with the appearance of root fibers, including some identified VIIth motor axons, associated with the primordial VII/VIIIth ganglia. By 3 days, some vestibular and VIIth nerve fibers could be identified by their ultrastructure and relative positions within the marginal zone and nerve roots. However, it was not until 4 days that the presumptive tangential nucleus acquired its orderly, characteristic organization. Although synapses were rare from 2 to 4 days, attachment plaques and coated pits were observed commonly between structures, especially between future synaptic structures. Thus, we confirm that synapse formation begins at 5 days. This represents the first detailed ultrastructural study of cranial sensory nerve ingrowth into the medull.

ISSN:0092-7317    

DOI:10.1002/cne.903100108

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

年代:1991

数据来源: WILEY

摘要:

AbstractTo accumulate phylogenetic information on the central histaminergic system, we investigated the histaminergic system in the brain of a teleost, the jack mackerel (Trachurus trachurus), using the indirect immunofluorescent method with antiserum against histamine. A small number of histamine‐ immunoreactive cell bodies were observed in the posterior hypothalamus around the posterior recess. Histamine‐immunoreactive fibers innervated the telencephalon, diencephalon, tegmentum, and rostral part of the medulla oblongata. The immunoreactive fibers were very sparse or absent in the olfactory bulb, optic tectum, cerebellum, caudal part of the medulla oblongata, spinal cord, and hypophysis. Ascending fiber bundles were seen in the basal hypothalamus, supplying fiber collaterals to the telencephalon and diencephalon, whereas descending fibers were observed in the midline of the lower brainstem. These findings suggest that the central histaminergic system of the jack mackerel is homologous to those of mammals, reptiles, and amphibians, although poorly developed compared with them. The histamine‐immunoreactive neuronal cell bodies found in the border area between the mesencephalon and rhomb encephalon of the river lamprey were not detected in the brain of the jack ma

ISSN:0092-7317    

DOI:10.1002/cne.903100109

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe expression of nerve growth factor receptor (NGFR) transcripts was investigated with in situ hybridization techniques in the CNS of chick embryos from 3 days of incubation (E3) to 14 days posthatch (P14). The time course and distribution of NGFR expression was compared with the development of the cholinergic phenotype. Cholinergic properties were assessed by immunolabeling for choline acetyltransferase (ChAT) and histochemistry for acetylcholinesterase (AchE) activit.NGFR transcripts are expressedtransientlyin the inner plexiform layer and ganglion cell layer of the retina (E4–P1), neostriatum and hippocampus (E18), infundibular hypothalamus (E7–18), spiriform complex (E9–15), layers 2,3 (E9–18), and 10 (E11–18) of the optic tectum, nucleus mesencephalicus profundus, pars ventralis (E9–18), parvicellular isthmic nucleus (E7–P1), magnocellular isthmic nucleus (E9‐E18), nucleus semilunaris (E7–18), isthmo‐optic nucleus (E7–P14), rostral motor nuclei (E5–18), developing cerebellum (E7–15), internal granule cell layer (E11–18) and Purkinje cell layer (E15–P14) of the cerebellar cortex, and the inferior olivary nucleus (E9–15). A small number of neuronal populations with embryonic expression of NGFR remain strongly NGFR‐positive in the posthatch animal: habenular nuclei (labeled after E5), nucleus subrotundus (after E9), mesencephalic trigeminal nucleus (after E5), caudal parts of locus ceruleus and nucleus subceruleus (after E7), medullar reticular nuclei (after E11), and motor nuclei IX, X, and XII (after E9).The majority of neuronal populations with NGPR expression show cholinergic properties in development, and NGFR expression always precedes the onset of ChAT immunoreactivity. Postnatal expression of growth factor receptors is largely confined to neurons of the reticular type. NGFR expression in avian CNS nuclei differs from that in mammals. Early loss of NGFR expression in the cholinergic basal forebrain (which remains strongly NGFR positive in mammals) and persistent NGFR expression in parts of the avian locus ceruleus indicate changes of growth factor receptor expression and growth factor requirements in phylogeny. Knowledge of the time and distribution of NGFR expression in the chick embryo will facilitate the assessment of specific functions of NGF and NGF‐like molecules in an embryonic model with easy a

ISSN:0092-7317    

DOI:10.1002/cne.903100110

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

年代:1991

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.903100102

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

年代:1991

数据来源: WILEY