摘要:

AbstractAlthough the ascidian tadpole larva harbors a prospectively valuable prototype of the chordate nervous system, with extensively characterized neural plate cell lineages, the simple cellular composition of the resultant central nervous system (CNS) is not documented in detail. The average total number of cells in the larval CNS ofCiona intestinalisis 335 (range ±4, n = 3), 65 or 66 of which reside in the nerve cord of the tail. The estimates were made by tracing and counting the number of nuclei in serial semithin (1 m̈m) sections cut longitudinally through three larvae, fixed no later than 2 hours after hatching. Within a single fourth larva,L4, 266 cells constituted the CNS in the trunk region of the larva, 45 of which occurred within the visceral ganglion, 215 in the sensory vesicle, and 6 in the neck between the two. Each cell was assigned to one of thirteen categories. Most (182, roughly 68%) are classified as ependymal, a specialized non‐neural cell peculiar to embryonic and larval chordates, from their position lining the cavities of the neural tube's elaborations or from clear similarities in the cytological appearance to those that do. Five cells are accessory cells of the sensory structures: three lens cells and a pigment‐cup cell in the ocellus, and a single pigment cell in the otolith. Of the remaining 79 cells, 36 are sensory, 17 receptors in the ocellus and 19 presumed hydrostatic pressure receptors; these lie on the right and left, sides of the sensory vesicle, respectively. Eighteen of the visceral ganglion cells have been tentatively classified as neurons, as have the remaining 25 cells which form two clusters in the posterior region of the sensory ve

ISSN:0092-7317    

DOI:10.1002/cne.903090402

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

年代:1991

数据来源: WILEY

摘要:

AbstractNeuropeptide Y (NPY)‐containing neurons are known to be highly vulnerable following sustained electrical stimulation in rats and in humans suffering from temporal lobe epilepsy. This has been related to a strong excitatory input. In contrast, there is evidence that neurons containing calcium‐binding proteins exhibit a high resistance under experimental seizure and hypoxia conditions. The aim of this study was to determine the coexistence of NPY and calcium‐binding proteins in inhibitory neurons of the primate fascia dentata and their synaptic connections. Vibratome sections of hippocampi of African green monkeys (Cercopithecus aethiops) were immunostained with antibodies against NPY, PARV, and CB. A quantitative coexistence study was performed for NPY and PARV on consecutive semithin sections. In contrast to the rodent hippocampus, NPY‐immunoreactive neurons were found exclusively in the hilus of fascia dentata with horizontally oriented dendrites which did not extend into the granular and molecular layer. Conversely, PARV‐immunoreactive neurons were also present in the granular and inner molecular layer and extended their dendrites far out in the molecular layer and the hilus. Axon terminals immunoreactive for NPY were mostly concentrated in the middle and outer molecular layer and the hilar region and were rare in the granular layer. PARV‐immunoreactive boutons were basically restricted to the granular layer where they formed typical baskets. The antibody against calbindin stained almost exclusively granule cells. Coexistence of NPY‐ and PARV‐immunoreactivity was found only in hilar neurons and was rare (9 out of 152 cells analyzed). These results suggest that most NPY‐immunoreactive neurons do not contain calcium‐binding proteins. NPY‐containing neurons exhibited ultrastructural characteristics as described for inhibitory neurons. Their dendrites were only sparsely contacted by mostly asymmetric synaptic terminals, including a very small number of mossy fiber axon terminals. In turn, numerous NPY‐immunoreactive axon terminals formed symmetric synapses with spines and dendritic shafts of unlabeled neurons in the middle and outer molecular layer, whereas no contact with granule cell bodies was evident. Thus, we conclude that the vulnerability of NPY‐containing inhibitory neurons may be due more to the lack of calcium‐binding proteins than to a strong excitatory innervation. As their axons may contribute to the inhibitory control of the major excitatory input from the entorhinal cortex, their loss following overstimulation may play a role in perpetuating h

ISSN:0092-7317    

DOI:10.1002/cne.903090403

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe cytoarchitecture and distributions of seven neuropeptides were examined in the the bed nucleus of the stria terminalis (BST), substantia innominata (SI), and central and medial nuclei of the amygdala of human and monkey to determine whether neurons of these regions form an anatomical continuum in primate brain. The BST and centromedial amygdala have common cyto‐ and chemo‐architectonic characteristics, and these regions are components of a distinct neuronal complex. This neuronal continuum extends dorsally, with the stria terminalis, from the BST and merges with the amygdala; it extends ventrally from the BST through the SI to the centromedial amygdala. The cytoarchitectonics of the BST‐amygdala complex are heterogeneous and compartmental. The BST is parcellated broadly into anterior, lateral, medial, ventral, supracapsular, and sublenticular divisions. The central and medial nuclei of the amygdala are also parcellated into several subdivisions. Neurons of central and medial nuclei of the amygdala are similar to neurons in the lateral and medial divisions of the BST, respectively. Neurons in the SI form cellular bridges between the BST and amygdala. The BST, SI, and amygdala share several neuropeptide transmitters, and patterns of peptide immunoreactivity parallel cytological findings. Specific chemoarchitectonic zones were delineated by perikaryal, peridendritic/perisomatic, axonal, and terminal immunoreactivities. The results of this investigation demonstrate that there is a neuronal continuity between the BST and amygdala and that the BST‐amygdala complex is prominent and discretely compartmental in forebrains of human and

ISSN:0092-7317    

DOI:10.1002/cne.903090404

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe organization of projections from nucleusrobustus archistriatalis(RA) was mapped by a combination of anatomical tracer techniques. After injections of retrograde tracers in the syringeal part of the hypoglossal motor nucleus (nXIIts), labelled cells were seen in ipsilateral RA, in agreement with previous work. However, a shallow band in the dorsal and dorsocaudal part of RA did not contain labelled cells. Cells in this “cap” area were labelled following tracer injections in the dorsomedial nucleus of midbrain ICo (DM), the other known target of RA projections. The topography of outputs to nXIIts was further examined by making small injections of retrograde tracer into physiologically identified control zones for individual syringeal muscles in nXIIts. The distribution of labelled cells in RA revealed bands of cells that cross RA in approximately horizontal layers and project to different parts of nXIIts. This topography was confirmed with the anterograde tracer PHA‐L. Thus RA contains two functional subdivisions, one related to midbrain centers for vocalization and the other directly controlling syringeal motorneurons. The latter area can be further divided into zones that preferentially engage particular syringeal mu

ISSN:0092-7317    

DOI:10.1002/cne.903090405

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe toad glutaeus magnus muscle receives a topographical innervation dependent on the rostrocaudal origins of glutaeus motor axons on the spinal cord. The same projection is re‐established in adult animals after cutting the glutaeus muscle nerve and allowing regenerating axons to reinnervate the muscle (Brown and Everett (1990) J. Comp. Neurol.292:363–372). To determine whether the topographically selective reinnervation of the glutaeus muscle comes about because of genuine positional qualities associated with the pre‐ and post‐synaptic tissues, we undertook two different experimental procedures: first, the nerve supply to the muscle was cut and redirected to ensure that regenerating axons entered the muscle via entirely novel pathways; and second, the triceps femoris nerve was cut so that the glutaeus muscle was reinnervated from a large pool of motor axons which were mostly foreign but segmentally appropriate. The motor projection to the muscle was determined by the glycogen depletion procedure; single glutaeus motor axons were repetitively stimulated in vitro to deplete muscle fibres of their stores of glycogen. The spatial location of fibres belonging to single motor units could then be determined by staining sections of the muscle histochemically for glycogen. A similar to normal projection was re‐established after both experiments in that rostrally located motor axons innervated mostly the ventral portion of the muscle and caudal axons mostly the dorsal portion of the muscle. “Intermediate” axons synapsed predominantly with fibres in the middle of the muscle. Furthermore, the arrangement of fibre types in the muscle could not fully account for the reformation of the topographical projection by a type matching mechanism, although a secondary role for fibre types in the subsequent refinement of the projection was clearly suggested by our findings. Our results provide evidence for a distinction between at least two determinants that influence the reinnervation of muscle: positional cues and fibre types, with the former taking precedence ov

ISSN:0092-7317    

DOI:10.1002/cne.903090406

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe anterior hypothalamus‐preoptic area and ventromedial hypothalamus are sexually dimorphic in the reproductively active whiptail lizardCnemidophorus inornatus.The anterior hypothalamus‐preoptic area, which is involved in the control of male‐typical copulatory behaviors, is larger in males, whereas the ventromedial hypothalamus, which is involved in the control of female‐typical receptivity, is larger in females. In the parthenogenetic whiptail lizardC. uniparens, which is a direct descendant ofC. inornatusand exhibits both male‐like and female‐like pseudosexual behaviors, both brain areas are comparable in size to those of femaleC. inornatus.This study was conducted to determine whether these brain areas change in size in either species or sex during a time of year when these animals are reproductively inactive, or after removal of the gonads. In maleC. inornatusboth brain areas changed during reproductive inactivity (either seasonally or surgically induced) and became equivalent to the size characteristic of reproductively active femaleC. inornatus.When corrected for brain size, the anterior hypothalamus‐preoptic area was significantly smaller in intact hibernating and castrated males than in intact males from the summer breeding season. Conversely, the ventromedial hypothalamus was significantly larger in intact hibernating and castrated males than in intact males from the summer breeding season. The two brain areas were not significantly different among the groups of femaleC. inornatusor parthenogeneticC. uniparens.These results suggest that (1) the brain of whiptail lizards may differentiate seasonally and (2) the female state may be a neutral one to which the male brain reverts during reproducti

ISSN:0092-7317    

DOI:10.1002/cne.903090407

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe peptidergic and serotoninergic innervation of the rat dura mater was investigated by reacting dural wholemounts immunohistochemically with antibodies to calcitonin gene‐related peptide (CGRP), substance P (SP), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), and serotonin (5‐HT). CGRP and SP innervations of the dura were robust and the patterns of distribution of these neuropeptides were essentially the same. The majority of the fibers were perivascular and distributed to branches of the anterior and middle meningeal arteries and to the superior sagittal and transverse sinuses. Other CGRP/SP fibers appeared to end “free” within the dural connective tissue. NPY‐immunoreactive fibers were extremely numerous and also distributed heavily to the branches of the meningeal arteries, the venous sinuses, and to the dural connective tissue. The pattern of NPY innervation resembled in many ways that of CGRP/SP; however, NPY innervation of the sinuses was greater and NPY perivascular fibers supplying the meningeal arteries formed more intimate contacts with the walls of the vessels. The pattern of VIP innervation was, in general, similar to that observed for the three previous neuropeptides; however, the overall density was considerably less. Small to moderate numbers of serotoninergic nerve fibers were observed in some, but not all, of the duras processed for 5‐HT. The latter fibers were almost exclusively perivascular in distribution. Dural mast cells were prominently stained in the 5‐HT preparations because of their serotonin content. Mast cells were also labeled in a nonspecific fashion in some of the tissues reacted immunohistochemically for neuropeptides; some of them were located in close apposition to passing nerve fibers.This study represents, to our knowledge, the first comprehensive work on the peptidergic and serotoninergic innervation of the mammalian dura mater. The results should increase our understanding of the roles that these fibers play in normal dural physiology and of their potential interactions in the pathogenesis of vasc

ISSN:0092-7317    

DOI:10.1002/cne.903090408

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

年代:1991

数据来源: WILEY

摘要:

AbstractWe localized serotonin (5‐HT), leu‐enkephalin (LENK), and tyrosine hydroxylase (TH) immunoreactive cells in the brain of a holocephalian,Hydrolagus colliei, by use of antibodies made in rabbit and the peroxidase‐antiperoxidase technique. Only three locations contained TH+ cells, the caudal myelencephalon, the locus coeruleus, and the diencephalon. Of these locations, the diencephalon contained the most cells and the locus coeruleus the least cells. The caudal TH+ myelencephalic cells formed a single large group that spanned both the dorsal and ventral portions of the brain (A1A2). The diencephalic TH+ cells were located in the posterior tuberculum, in the ventromedial and ventrolateral thalamic nuclei, and in the inferior lobe of the hypothalamus.Hydrolagusdiffered from mammals and the elasmobranchs, their sister group, in that no substantia nigra (A9), ventral tegmental area (A10), or A5 cell group was found.Distribution of LENK+ and 5‐HT+ cells were similar to each other; the raphe nuclei contained most of the 5‐HT+ and LENK+ cells. These 5‐HT+ and LENK+ cells were found at all rostrocaudal levels of the myelencephalon. The nucleus reticularis magnocellularis, reticularis magnocellularis lateralis, the ventral met‐ and mesencephalon (B7 and B9 cell groups), the hypothalamus, and the pretectal area contained additional 5‐HT+ and LENK+ cells. The solitary complex contained LENK+ cells but not but 5‐HT+ cells. A dorsal raphe nucleus, which is the largest 5‐HT+ cell group in mammals, was absent mHydrolagus.A dorsal raphe nucleus is present in one galeomorph shark radiation but is absent in three radiations of batoids (rays, skates, and guitarfish). Thus even within cartilaginous fish, there are differences in the distribution of neurochemicals and possibly nuclei

ISSN:0092-7317    

DOI:10.1002/cne.903090409

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.903090401

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

年代:1991

数据来源: WILEY