摘要:

AbstractThe bed nucleus of the stria terminalis (BST) sends a dense projection to the parabrachial nucleus (PB) in the pons. The BST contains many different types of neuropeptidelike immunoreactive cells and fibers, each of which exhibits its own characteristic distribution within cytoarchitecturally distinct BST subnuclei. Corticotropin releasing factor (CRF)‐, neurotensin (NT)‐, somatostatin (SS)‐, and enkephalin (ENK)‐like immunoreactive (ir) neurons are particularly numerous within areas of the BST that project to the PB. In this study, we use the combined retrograde fluorescence‐immunofluorescence method to determine whether neurons in the BST that project to the PB contain these immunoreactivities. After Fast Blue injections into PB, retrogradely labeled neurons were numerous throughout the lateral part of the BST, particularly in the dorsal lateral (DL) and posterior lateral subnuclei. Retrogradely labeled neurons were also present in the preoptic, ventral lateral, and supracapsular BST subnuclei and in the parastrial nucleus. Many of the CRF‐ir, NT‐ir, and SS‐ir neurons in DL were retrogradely labeled. A few double‐labeled cells of each type were also found in the posterior lateral, ventral lateral and supracapsular BST subnuclei ENK‐ir neurons were never retrogradely labeled. Our results show that BST neurons that project to the PB stain for the same neuropeptides as those in the central nucleus of the amygdala (CeA) that project to the PB, demonstrating further the close anatomical relations between t

ISSN:0092-7317    

DOI:10.1002/cne.902830302

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

年代:1989

数据来源: WILEY

摘要:

AbstractImmunoelectron microscopy was used to examine the synaptic organization of enkephalinlike‐immunoreactive amacrine cells in the goldfish retina. Enkephalin‐immunostained processes sometimes contained dense‐cored vesicles (115–145 nm) in addition to a generally homogeneous population of small, round, clear synaptic vesicles. A total of 194 synaptic relationships were observed that involved the immunostained processes of enkephalin‐amacrine cells. The large majority of these were observed in sublayer 5 of the inner plexiform layer. In greater than 95% of the synaptic relationships, the enkephalin‐immunostained profile served as the presynaptic element. In 58.8% of these relationships, enkephalin processes synapsed onto amacrine cell processes, while 30.4% of their synapses were onto processes that lacked synaptic vesicles. They also occasionally formed synaptic contacts (6.7%) onto the somas of cells located either in the inner nuclear or in the ganglion cell layers. Enkephalin profiles received synaptic input only from amacrine cells (4.1%), while no direct synaptic interaction was observed between enkephalin processes and bipolar cells. However, in sublayer 1, enkephalin profiles were found to synapse onto amacrine cell processes that were presynaptic to bipolar cell terminals. In the proximal inner plexiform layer, enkephalin processes were presynaptic to amacrine cell processes that as a group surrounded and sometimes provided synaptic input to extremely large and round bipolar c

ISSN:0092-7317    

DOI:10.1002/cne.902830303

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe connections of the superficial pretectum and of nucleus isthmi were examined in a percomorph teleost,Lepomis cyanellus. Horseradish peroxidase was injected either with a pin into the parvicellular nucleus of the superficial pretectum or pressure injected into nucleus isthmi; the isthmal injections retrogradely labelled the neurons of the magnocellular nucleus of the superficial pretectum. Two main visual pathways can be recognized: The first projects from the retina to the parvicellular nucleus, and then to the intermediate nucleus of the superficial pretectum, the inferior raphe nucleus, and the trochlear nucleus. The second projects from the retina via the optic tectum to the magnocellular nucleus of the superficial pretectum, and from there to nucleus isthmi and the lateral thalamic nucleus; nucleus isthmi and the lateral thalamic nucleus project back to the optic tectum, and nucleus isthmi also projects back to the magnocellular nucleus. The two pathways are interconnected to some extent because both nucleus isthmi and the optic tectum project to the parvicellular nucleus; nevertheless, we suggest that they may be functionally and evolutionarily distinct. Compared to percomorphs, the first pathway appears reduced in cyprinid teleosts such as goldfish. Furthermore, the magnocellular nucleus of the second pathway is completely different in cyprinids, both in cellular architecture and in efferent connections. A phylogenetic analysis suggests that cyprinid ancestors went through a period of reduced vision and that the magnocellular nucleus of the superficial pretectum in modern cyprinids has been either extensively modified from the primitive condition or lost entirely and replaced by a superficially similar structure.

ISSN:0092-7317    

DOI:10.1002/cne.902830304

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe homotopic and heterotopic callosal connections in the forelimb representations of the second (SII) and fourth (SIV) somatic sensory areas of cats were investigated by means of the axonal transport of horseradish peroxidase (HRP) in conjunction with microelectrode recording. The tracer was injected in the electrophysiologically identified hand and/or digit zone of SII (six cats) or SIV (four cats). The homotopic area in the contralateral hemisphere was explored with microelectrodes in five animals (three injected in SII and two in SIV) to map neuronal receptive fields. The aim was to correlate in the same experimental case the topography of labelled callosal neurons with the physiological map of the forelimb. Labelled cells and recording sites were plotted on planar maps reconstructed with the aid of a computer from serial coronal sections from the anterior ectosylvian gyrus.After SII injections, labelled callosal neurons were observed throughout the forelimb representation in the contralateral area, but in the tangential plane their distribution was uneven. Each somatotopic zone composing the forelimb map, that is, the arm, hand, and digit zones, contained several subzones in which callosal neurons were either dense or rare. Microelectrode explorations showed that receptive fields mapped from callosal and relatively acallosal subzones representating the same body part were similar in extent and location. After SIV injections, labelled callosal neurons were observed throughout the forelimb and proximal body representation of the contralateral area. Although slight regional variations in the density of labelled cells were apparent, no subzones bare of callosal labelling were observed in SIV. In both SII and SIV, callosal neurons were concentrated mainly in layer III, but a significant number was also evident in the infragranular layers. After HRP injections in the digit zone of SII or SIV, labelled cell bodies were also observed in heterotopic areas of the contralateral hemisphere. Most of these neurons were clustered in the medial bank of the coronal sulcus and in two other heterotopic cortical regions lying, respectively, in the anterior suprasylvian sulcus and in the lateral branch of the ansate sulcus. Some callosal cells interconnecting SII and SIV were also labelled. The results show that the distal forelimb zones in SII and SIV are callosally connected with the respective homotopic zones and with several somatosensory fields located heterotopically in the contralateral hemisphere.

ISSN:0092-7317    

DOI:10.1002/cne.902830305

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

年代:1989

数据来源: WILEY

摘要:

AbstractAlthough a well‐developed plexus of nerves and ganglia is known to be present in the wall of the gallbladder, little has previously been learned about the function or organization of this innervation. The current study was undertaken in order to evaluate the hypothesis that the ganglionated plexus of the gallbladder is analogous to elements of the enteric nervous system (ENS). The ganglionated plexus of the gallbladder was found to resemble closely the submucosal plexus of the small intestine in its organization into two irregular anastomosing and interwoven networks of ganglia, in the numbers of neurons per ganglion, and in the manifestation of histochemically demonstrable acetylcholinesterase activity in virtually all ganglion cells. In common with enteric ganglia, laminin immunoreactivity was observed to be excluded from the interiors of gallbladder ganglia, which were surrounded by a periganglionic laminin‐immunoreactive sheath. As in the submucosal plexus, intrinsic substance P‐, vasoactive intestinal polypeptide (VIP)‐, and neuropeptide Y (NPY)‐immunoreactive neurons were seen in the ganglionated plexus of the gallbladder. Extrinsic nerves in the gallbladder that degenerated following chemical sympathectomy with 6‐hydroxydopamine (6‐OHDA), and which contained NPY, tyrosine hydroxylase (TH), and dopamine‐β‐hydroxylase (DBH) immunoreactivities, formed a perivascular plexus closely associated with blood vessels. Endogenous catecholamines could also be demonstrated in these perivascular nerves by aldehyde‐induced histofluorescence. In addition to perivascular nerves, paravascular nerve bundles were observed that were loosely associated with vessels, did not degenerate following administration of 6‐OHDA, and contained NPY immunoreactivity. Other paravascular nerves, probably visceral sensory axons, coexpressed substance P and calcitonin‐generelated peptide (CGRP) immunoreactivities. The ganglionated plexus of the gallbladder resembled enteric ganglia in having intrinsic 5‐hydroxytryptamine (5‐HT)‐immunoreactive cells and highly varicose nerve fibers. The 5‐HT‐immunoreactive gallbladder axons were, like those of the gut, resistant to 6‐OHDA, and separate from fibers that expressed TH immunoreactivity. Differences between the ganglionated plexus of the gallbladder and enteric ganglia of the small intestine included in the gallbladder are (1) the presence of TH‐immunoreactive cells that contain an endogenous catecholamine, but not DBH; (2) DBH‐immunoreactive neurons, some of which coexpress substance P immunoreactivity, but which contain neither a catecholamine nor TH immunoreactivity; (3) an apparent absence of CGRP‐immunoreactive cell bodies. Retrograde tracers injected into the wall of the gallbladder revealed a direct innervation of the organ from neurons in ganglia of the myenteric plexus of the duodenum, in addition to neurons in the dorsal motor nuclei of the vagus, the celiac ganglion, and bilaterally in the nodose and T5‐T11dorsal root ganglia. Because of its similar structure and receipt of a direct neural input from myenteric ganglia, the ganglionated plexus of the gallbladder should be regarded as an extension or division of the ENS; however, gallbladder‐specific specializations also occur. These specializations are similar to the regional differences found in

ISSN:0092-7317    

DOI:10.1002/cne.902830306

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe primary aim of this work was to investigate the properties of rapid axonal transport in regenerating myelinated axons in the sciatic nerve ofXenopus laevis, with particular attention to events at the junction between the proximal, intact axon (the “parent”) and the distal, newly formed axon (the “daughter”). Morphological studies indicated that all myelinated axons initiated regeneration and that at least 80% of these axons regenerated at a rate of 1 mm/day or greater (20°C). The ultrastructure of the junctional region was examined at regeneration times between 3 days and 20 weeks. The main qualitative change in the junctional axoplasm over this period was in its content of particulate organelles. At times up to 2 weeks regeneration, the junction contained abnormal numbers of 50 nm diameter vesicles and 10 nm granules. Between 2 and 5 weeks the junction showed in addition a peripheral rim of large membrane‐bounded organelles around a central core of microtubules and neurofilaments. At longer times the numbers of large membrane‐bounded organelles diminished and all junctions contained prominent accumulations of 10 nm granules. The rate of rapid axonal transport of protein was similar in parent and daughter axons. Compared to the parent axons, a 2–5 times greater amount of protein was deposited to a stationary phase in daughter axons. Specimens of nerve that were subjected to mechanical stress during the removal of the perineurium showed a large accumulation of rapidly transported protein in the region of the crush at regeneration times up to 40 days; some of the accumulated protein was subsequently transported retrogradely. Video microscopy of isolated axons supplied evidence that the transport deficit in mechanically stressed nerve was a partial block of anterograde vesicle transport, plus a reversal of anterograde transport, at the junction of parent with daughter axons. No structural changes were detected in mechanically stressed nerve. The results show that the junction between parent and daughter myelinated axons is a region with distinct morphology at which the dynamics of anterograde axonal transport may chang

ISSN:0092-7317    

DOI:10.1002/cne.902830307

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

年代:1989

数据来源: WILEY

摘要:

AbstractCobaltous‐lysine applied to the goldfish optic nerve backfilled retinal ganglion cells and their axons. Confined to the ventronasal and ventrotemporal retina was a small population of retinal ganglion cells whose axons traveled dorsally and parallel to the retinal margin. On reaching the boundary between dorsal and ventral retina, the axons arched, joined radially oriented bundles of axons, and traveled toward the optic disk. Control studies showed that the axons came from retinal ganglion cells rather than from retinopetal cells. The somatic area of retinal ganglion cells (RGCs) with circumferential axons was 30–50 μm, and was similar to that of average ganglion cells. The axons of these cells coursed between the optic fiber and ganglion cell layers or between the ganglion cell and inner plexiform layers. Many somata were displaced slightly toward the inner plexiform layer, but were not really displaced ganglion cells. The aberrant axonal trajectory may be related to the slightly displaced location of the cell. However, ganglion cells that are displaced to the edge of the inner nuclear layer usually have radially coursing axons.We digitized the coordinates of the bending points and the dorsoventral retinal boundary. On average, the bending points occurred within 100 μm of the dorsoventral retinal border. These findings suggest that some molecular, rather than mechanical, factor at the dorsoventral retinal boundary alters the course of the circumferential axons. Furthermore, because there are cells with circumferential axons throughout the ventral retina, the data imply that at least ventral RGC axons avoid mingling with the axons from dorsal

ISSN:0092-7317    

DOI:10.1002/cne.902830308

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

年代:1989

数据来源: WILEY

摘要:

AbstractAn antiserum against the inhibitory transmitter substance γ‐aminobutyric acid (GABA) was used to investigate the distribution of GABAergic nerve terminals and cell bodies in the lateral cervical nucleus (LCN) of the cynomolgus monkey. Light microscopic immunohistochemistry demonstrated GABA‐immunoreactive puncta, suggestive of nerve terminals, scattered throughout the LCN. The terminal‐like profiles are often present along the somata of unlabeled neurons, but most are located in the neuropil. GABA‐immunoreactive neurons are present in the LCN, but constitute a very small number of the LCN neurons. Electron microscopy showed that the GABA‐positive neurons are small with a relatively large nucleus. They are contacted by few somatic boutons. Numerous GABA‐immunoreactive terminals containing densely packed round to oval synaptic vesicles were also found. Most GABA‐positive terminals make synaptic contact with dendrites, but synapses with cell bodies are also present. Synaptic contacts between labeled and unlabeled terminals were not observed. Some GABA‐positive terminals make contact with GABA‐positive neurons.The present findings suggest that GABA is a major inhibitory transmitter substance in the LCN of the monkey. However, in comparison with other somatosensory relay nuclei, there are few GABA‐immunoreactive neurons in the LCN. This may imply tha the GABA‐positive neurons branch extensively in the LCN or that an extrinsic source of

ISSN:0092-7317    

DOI:10.1002/cne.902830309

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

年代:1989

数据来源: WILEY

摘要:

AbstractIn an effort to understand naturally occurring neuronal death in the developing isthmo‐optic nucleus, we have accentuated one of its most probably causes, failure to receive adequate trophic maintenance from the axonal terminal zone in the retina, and have studied the dying neurons ultrastructurally. Retrograde trophic maintenance was blocked by means of intraocularly injected colchicine, which caused all the isthmo‐optic neurons to die by just one of the two or more kinds of cell death that they undergo during normal development. The present paper deals with the very prominent cytoplasmic aspects of this kind of cell death, notably the uptake of exogenous horseradish peroxidase and autophagy. There were also nuclear changes, which are dealt with mainly in the accompanying paper (Clarke and Hornung,J. Comp. Neurol. 283: 438–449, '89).Numerous cytoplasmic vacuoles occurred in both soma and dendrites, and they were of three main kinds, of which the smallest (less than 0.5 μm diameter) had unstructured contents, whereas the larger two (1–2 μm and 2–7 μm) were secondary lysosomes (mostly residual bodies).Intravascularly injected horseradish peroxidase labeled all three kinds of vacuole but not the free cytoplasm, indicating that the uptake was by endocytosis rather than by leakage through holes in the membrane, as is confirmed by our failure to detect any such holes. We suspect that the smallest vacuoles are the primary endosomes, that these subsequently fuse with vacuoles of the intermediate kind, and that the largest vacuoles are formed by the fusion of these latter. The purpose of the endocytosis may be to channel the plasma membrane piecemeal into the lysosomes for

ISSN:0092-7317    

DOI:10.1002/cne.902830310

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

年代:1989

数据来源: WILEY

摘要:

AbstractThymidine autoradiography has been used at light and electron microscopic levels to elucidate intracellular events during the death in chick embryos of isthmo‐optic neurons deprived of trophic maintenance from their axonal target organ, the retina. When the intense cytoplasmic vacuolization described in the accompanying paper (Hornung, Koppel, and Clarke,J. Comp. Neurol. 283: 425–437, '89) was beginning, the nuclei also underwent profound changes. They became more electron dense and shrank; their membranes became more sharply defined and convoluted; they sometimes contained pyknotic balls, but apparently only in the early stages of cell death; all lost more than half of their content of DNA, some of which was transferred to the largest kind of cytoplasmic vacuole. This transfer may have involved the budding off of nuclear regions containing pyknotic balls. The cells continued to survive for a day or 2 after these severe losses of nuclear DNA, sustaining intense endocytic activity. Pronounced unscheduled DNA synthesis occurred in the nuclei, but this was insufficient to replace the lost

ISSN:0092-7317    

DOI:10.1002/cne.902830311

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

年代:1989

数据来源: WILEY