摘要:

AbstractSerial 50 μm Nissl‐stained sections through the midbrain and pontine central gray of four adult humans (mean age 56 years, mean postmortem delay 3 hours) were analysed and the subnuclei of the dorsal raphe nucleus (DR) delineated on the basis of neuronal morphology and density. Five subnuclei were apparent: the interfascicular, ventral, ventrolateral, dorsal, and caudal. The area of each subnucleus was measured in sections selected at regular intervals throughout the length of the DR. The number of neurons was counted and their density within each subnucleus calculated. The dorsal subnucleus was the largest and contained the majority of neurons but had the lowest neuronal density. The ventrolateral subnucleus had the highest density of neurons. A total of 235,000 ± 15,000 neurons (average of 1,200 ± 200 neurons per section) were found within a volume of 71.3 ± 4.5 mm3of DR with a mean neuronal density of 3,300 ± 200 neurons/mm3. Morphometric and morphological analysis of DR neurons revealed four distinct neuron types: round, ovoid, fusiform, and triangular. These types of neurons characterized particular subnuclei. The location and boundaries of the subnuclei of the human dorsal raphe are presented in the form of an atlas. The subdivisions described are similar to that described in other mammals. On the basis of this information the location of particular projection neurons within the human dorsal raphe can be predicted and the effects of disease on this nucleus may be fo

ISSN:0092-7317    

DOI:10.1002/cne.903010202

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

年代:1990

数据来源: WILEY

摘要:

AbstractThis study reports that zn‐1, a monoclonal antibody, labels hair cells but not supporting cells in the inner ear and the lateral line of the axolotl salamander,Ambystoma mexicanum.Zn‐1 immunocytochemically labels the cytoplasm and stereocilia of mature hair cells in the sacculus, in the utriculus, and in the mechanoreceptive neuromast organs of the lateral line. Lower levels of labeling mark newly formed hair cells in the periphery of the sacculus and in regenerating neuromasts. Zn‐1 also selectively labels neuronal processes and perikarya in the lateral line nerves and ganglia and the VIIIth cranial nerve and ganglion. Processes and perikarya are labeled by zn‐1 in the dorsolateral medulla oblongata, at sites of termination of the afferent octaval and lateral line neurons. Western blot analysis revealed that zn‐1 labels one or more proteins with molecular weights of 80 and 160 kDa. The identity of these protein bands remains to be determined. The presence of a specific epitope expressed in both hair cells and neurons, but not in supporting cells, in the vestibular and auditory epithelia of the ear and in the mechanoreceptive neuromasts of the lateral line suggests shared cytogenetic heritages. These findings are consistent with a close evolutionary relationship between otic and lateral line senses, such as that inherent to the theoretical evolutionary scheme outlined in van Bergeijk's “acousticolateralis hypothesis.” The protein recognized by zn‐1 is as yet unidentified, but its conservative evolution suggests that it may serve an important function in the statoacoustic and later

ISSN:0092-7317    

DOI:10.1002/cne.903010203

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

年代:1990

数据来源: WILEY

摘要:

AbstractAmacrine cells of the goldfish retina were characterized electrophysiologically and subsequently labelled by intracellular injection of horseradish peroxidase. An attempt was made to broaden the electrophysiological classification of the cells. Light‐evoked sustained amacrice cell responses were divided into two subtypes depending on colour opponency. Colour‐coded responses (red/depolarizing and green/hyperpolarizing) were found to arise in amacrine cells possessing highly polarized dendritic fields; the dendrites were monostratified in the proximal half (sublaminab) of the inner plexiform layer. Non‐colour‐opponent sustained responses also arose in monostratified units, but the level of dendritic ramification was in sublaminaaorb(hyperpolarizing or depolarizing units, respectively). Transient (ON‐OFF) responses were associated mainly with bi‐ or multi‐stratified or diffuse amacrine cells. Some variability was observed in the sizes of the dendritic fields in different sublaminae. There was a tendency for units with brisk components of responses to be narrowly stratified in the inner plexiform layer. Some units possessed “distant” dendrites. Several aspects of structure‐function correlation in amacrine

ISSN:0092-7317    

DOI:10.1002/cne.903010204

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe localization in the guinea pig enteric nervous system (ENS) of monoamine oxidase (MAO) types A and B was investigated at the light and electron microscopic levels. Immunocytochemistry was used to visualize the enzyme protein and histochemistry was employed to study catalytic activity. Type specificity was achieved in histochemical studies by using deprenyl (0.5 μM) to inhibit MAO‐B or clorgyline (0.1 μM) to inhibit MAO‐A. The distribution of MAO‐B immunoreactivity in the ENS corresponded to that of the sites of MAO activity found histochemically to be inhibited by deprenyl, but not clorgyline. MAO‐B was observed to be the primary type of MAO found in the intrinsic elements of the ENS and was located in subsets of neurons in both submucosal and myenteric plexuses. MAO‐B was not demonstrated immunocytochemically or histochemically in enteric glia, nor, at the light microscopic level, was there significant MAO‐B activity or immunoreactivity in serotonin (5‐HT)‐immunoreactive neuronal cell bodies. In the submucosal plexus about 50% of the neurons expressed MAO‐B; these neurons also contained neuropeptide Y (NPY) and/or calcitonin gene related peptide (CGRP), but not substance P or vasoactive intestinal polypeptide (VIP). About 10% of myenteric neurons were intensely reactive for MAO‐B; again MAO‐B was co‐localized with NPY and/or CGRP. In contrast to intrinsic neurons, extrinsic CGRP‐immunoreactive nerve fibers contained no demonstrable MAO activity or immunoreactivity. Moreover, the sympathetic innervation, identified as varicose axons that degenerated after administration of 6‐hydroxydopamine, contained abundant MAO‐A, but no MAO‐B activity or immunoreactivity. It is concluded that MAO‐B is characteristic of a subset of intrinsic enteric neurons, while MAO‐A is confined to the sympathetic innervation, which is extrinsic. At the electron microscopic level individual cells varied greatly in their degree of immuno‐ or cytochemically demonstrable MAO‐B, which was most concentrated on the outer membranes of mitochondria. MAO‐B immunoreactivity (but not cytochemical activity) was found on mitochondria in some serotoninergic perikarya identified by the simultaneous radioautographic detection of the uptake of3H‐5‐HT. Mitochondria in most serotoninergic axon terminals displayed both MAO‐B activity and immunoreactivity. Neurons receiving serotoninergic synapses often, but not invariably, contained MAO‐B. Inhibition of neither MAO‐B nor MAO‐A appeared to slow the disappearance of3H‐5‐HT loaded into enteric neurons significantly, even when intraneuronal storage of 5‐HT was inhibited with tetrabenazine. Alternative pathways for 5‐HT catabolism, such as glucuronidation, which do not occur in the brain, may be available to enteric serotoninergic neurons. The role of MAO‐B in enteric neurons th

ISSN:0092-7317    

DOI:10.1002/cne.903010205

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe anterograde and retrograde transport of horseradish peroxidase conjugated to wheat germ agglutinin (WGA‐HRP) was used to study the anatomical organization of descending projections from the mamillary body (MB) to the mesencephalon and pons at light and electron microscopic levels. Injections of WGA‐HRP into the medial mamillary nucleus resulted in dense anterograde and retrograde labeling in the ventral tegmental nucleus, while injections in the lateral mamillary nucleus resulted in dense anterograde labeling in the dorsal tegmental nucleus pars dorsalis and dense anterograde and retrograde labeling in the pars ventralis of the dorsal tegmental nucleus. Anterogradely labeled fibers in the mamillotegmental tract diverged from the principal mamillary tract in an extensive dorsocaudally oriented swath of axons which extended to the dorsal and ventral tegmental nuclei, and numerous axons turned sharply ventrally and rostrally to terminate topographically in the dorsomedial nucleus reticularis tegmenti pontis and rostromedial pontine nuclei. The anterograde labeling in these two precerebellar relay nuclei was distributed near the midline such that projections from the lateral mamillary nucleus terminated mainly dorsomedial to the terminal fields of projections from the medial mamillary nucleus.In the dorsal and ventral tegmental nuclei, labeled axon terminals contained round synaptic vesicles and formed asymmetric synaptic junctions primarily with small diameter dendrites and to a lesser extent with neuronal somata. A few labeled terminals contained pleomorphic vesicles and formed symmetric synaptic junctions with dendrites and neuronal somata. Labeled axon terminals were also frequently found in synaptic contact with retrogradely labeled dendrites and neuronal somata in the dorsal and ventral tegmental nuclei. These findings indicate that neurons in the dorsal and ventral tegmental nuclei are reciprocally connected with MB projection neurons. In the nucleus reticularis tegmenti pontis and medial pontine nuclei, labeled axon terminals contained round synaptic vesicles and formed asymmetric synaptic junctions primarily with small diameter dendrites. The present study demonstrates that projections from the medial and lateral nuclei of the MB are topographically organized in the mesencephalon and pons. The synaptic morphology of mamillotegmental projections suggests that they may have excitatory influences primarily on the distal dendrites of neurons in these brain regi

ISSN:0092-7317    

DOI:10.1002/cne.903010206

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

年代:1990

数据来源: WILEY

摘要:

AbstractSensory axons originating in peripheral tissues converge onto each segmental ganglion in the central nervous system (CNS) of the leech, where they segregate into well‐defined regions of the synaptic neuropil. Here we report on several aspects of the molecular and anatomical organizations of these afferent projections1that bear upon the hypothesis that surface markers are involved in organizing these axons as they grow into the CNS. First, we show that the distribution of some surface markers in the adult is restricted to axons of peripheral origin and is not present on the neighboring axons of central neurons. Second, we demonstrate that the number of afferents increases postembryonically as the leech increases in size, suggesting that at least some of the cues employed by afferent axons to grow to appropriate central targets must be present throughout the life of the animal. We then show, using anterograde axonal tracing and immunohistochemistry, that there is both convergence and divergence of afferent axons into highly specific regions of the neuropil. Lastly, we examine the distribution of surface markers present on different subsets of afferents and show that axons having one type of marker segregate from those having the second type.Our results, considered together with previous observations in this system, provide new clues about the organization of afferent projections in the nervous system of the leech. They also suggest how a relatively small number of molecular markers might mediate fiber‐fiber interactions to organize afferent axons as they grow into the

ISSN:0092-7317    

DOI:10.1002/cne.903010207

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe intrinsic organization of the mitral cell, external plexiform, and glomerular layers of the main olfactory bulb of the insectivore hedgehog were studied with the Golgi method. This study completes our previous description of the cell types in the granule cell layer in the same subject (López‐Mascaraque et al.,J. Comp. Neurol. 253:135–152, '86). In the present contribution the morphology of mitral, internal, and middle tufted cells is described with particular interest in the formation and arrangement of glomerular tufts by the primary dendrites, and the disposition of the secondary dendrites. Three types of intrinsic cells were found in the external plexiform layer: Van Gehuchten cells, satellite cells, and horizontal cells. All these cells display unusual patterns of branching processes that were difficult to classify as dendritic or axonal. The close relationship between some processes of the satellite cells with the mitral or tufted cell dendrites is noted, suggesting that these cells may be inhibitory in nature. The external tufted cells are described, and several aspects pertaining to their morphology were considered in order to distinguish them from periglomerular cells and from the remaining tufted cells. External tufted and periglomerular cells appear to be intrinsic neurons, having axons distributed in the periglomerular region, most probably devoted to relating different olfactory glomeruli. The arrangement of glomeruli in the glomerular layer and distinctive characteristics with respect to other mammals were considered from a comparative point of

ISSN:0092-7317    

DOI:10.1002/cne.903010208

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe aim of the present study was to determine the brainstem afferents and the location of neurons giving rise to monoaminergic, cholinergic, and peptidergic inputs to the cat trigeminal motor nucleus (TMN). This was done in colchicine treated animals by using a very sensitive double immunostaining technique with unconjugated cholera‐toxin B subunit (CT) as a retrograde tracer.After CT injections in the TMN, retrogradely labeled neurons were most frequently seen bilaterally in the nuclei reticularis parvicellularis and dorsalis of the medulla oblongata, the alaminar spinal trigeminal nucleus (magnocellular division), and the adjacent pontine juxta‐trigeminal region and in the ipsilateral mesencephalic trigeminal nucleus. We further observed that inputs to the TMN arise from the medial medullary reticular formation (the nuclei reticularis magnocellularis and gigantocellularis), the principal bilateral sensory trigeminal nucleus, and the dorsolateral pontine tegmentum.In addition, the present study demonstrated that the TMN received (1) serotonergic afferents, mainly from the nuclei raphe obscurus, pallidus, and dorsalis; (2) catecholaminergic afferent projections originating exclusively in the dorsolateral pontine tegmentum, including the Kölliker‐Fuse, parabrachialis lateralis, and locus subcoeruleus nuclei; further, that (3) methionin‐enkephalin‐like inputs were located principally in the medial medullary reticular formation (nuclei reticularis magnocellularis and gigantocellularis and nucleus paragigantocellularis lateralis), in the caudal raphe nuclei (Rpa and Rob) and the dorsolateral pontine tegmentum; (4) substance P‐like immunoreactive neurons projecting to the TMN were present in the caudal raphe and Edinger‐Westphal nuclei; and 5) cholinergic afferents originated in the whole extent of the nuclei reticularis parvicellularis and dorsalis including an area located ventral to the nucleus of the solitary tract at the level of the obex.In the light of these anatomical data, the present report discusses the possible physiological involvement of TMN inputs in the generation of the trigeminal jaw‐closer muscular atonia occurring during the periods of paradoxical

ISSN:0092-7317    

DOI:10.1002/cne.903010209

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

年代:1990

数据来源: WILEY

摘要:

AbstractAn immunocytochemical peroxidase‐antiperoxidase procedure using a purified polyclonal antibody raised against human placental aromatase was used to localize aromatase‐containing cells in the brain of three avian species: the Japanese quail, the ring dove, and the zebra finch. In quail and dove, immunoreactive cells were found only in the preoptic area and hypothalamus, with a high density of positive cells being present in the medial preoptic area, in the septal area above the anterior commissure, in the ventromedial nucleus of the hypothalamus, and in rostral part of the infundibulum. Immunoreactivity was weaker in zebra finches, and no signal could therefore be detected in the ventromedial and tuberal hypothalamus. The positive material was localized in the perikarya and in adjacent cytoplasmic processes, including the full length of axons always leaving a clear unstained cell nucleus. These features could be observed in more detail on sections cut from perfused brains and stained with an alkaline phosphatase procedure. The distribution of aromatase immunoreactivity was similar in the three species although minor differences were observed in the preoptic area. The localization of labelled neurons coincided with the distribution of aromatase activity as studied by in vitro radioenzyme assays on brain nuclei dissected by the Palkovits punch method. There was one striking exception to this rule: no immunoreactivity was detected in the zebra finch telencephalon, while assays had shown the presence of an active enzyme in several nuclei such as the robustus archistriatalis, the hyperstriatum ventrale pars caudale, and the hippocampus and area parahippocampalis. The origins of this discrepancy and the functional role of the aromatase observed in the axons are discus

ISSN:0092-7317    

DOI:10.1002/cne.903010210

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe extent of a region containing acoustically responsive neurons within the anterior ectosylvian sulcus and its relationship to surrounding gyral auditory cortical fields was examined in chloralose‐anaesthetized cats. Multiple microelectrode penetrations were made orthogonal to the middle and anterior ectosylvian gyral surfaces, and longer penetrations were made into the dorsal and ventral banks and fundus of the anterior ectosylvian sulcus. The quantitative and qualitative auditory response characteristics of neurons and neuron clusters in the sulcal banks and surrounding regions were mapped in detail, and the degree of overlap of auditory and visual neurons within the sulcus was determined by routinely testing for responsiveness to a gross light flash.The detailed results from three animals and a summary of all penetrations into the sulcus are presented. The anterior ectosylvian sulcal field (Field AES) lay deep within the banks and fundus of the posterior three quarters of the sulcus. A combination of changes in the auditory response characteristics of neurons (i.e., in optimal stimulus, latency, and frequency tuning), and the presence of visually responsive cells, distinguished this field from surrounding fields. The distinction between the anterior ectosylvian field and extensions of the nearby tonotopic fields (i.e., primary and anterior auditory fields) into the dorsal and ventral banks of the dorsoposterior sector of the sulcus was readily made on the basis of these characteristics. The distinction between the anterior ectosylvian field and extensions of the second auditory field into the ventral bank of the middle sector of the sulcus was more difficult and there were differences between animals in the transition between these fields. Anterior ectosylvian sulcal field responses did not extend into the dorsal bank in anterior parts of the sulcus but were restricted to fundal regions, an observation consistent with the presence of the fourth somatosensory field in the dorsal bank of this sector of the sulcus. The majority of penetrations into the sulcus revealed coextensive auditory and visual activity, an observation apparently at variance with the identification of a purely visual field in this region. Barbiturate anaesthesia, which has been used in experiments demonstrating an anterior ectosylvian visual area, was found to have a depressing effect on auditory responses within the anterior ectosylvian sulcal fiel

ISSN:0092-7317    

DOI:10.1002/cne.903010211

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

年代:1990

数据来源: WILEY