摘要:

AbstractEfferent projections of the medial cortex of the lizardsPodarcis hispanicaandGallotia stehliniiwere studied by examining the transport of horseradish peroxidase; results were correlated with those from Timm‐stained sections. Two efferent systems were found. The first reaches the distal part of the outer plexiform layer in the medial, dorsomedial, and dorsal cortices, i.e., zones that are negative to Timm staining, and possibly originates from horizontal fusiform neurons. The second reaches the Timm‐positive zones in the cortex and septum and is topographically arranged: theverticalportion of the intermediate and caudal medial cortex and the entire rostral medial cortex project to the inner two‐thirds of the outer plexiform layer of the dorsomedial cortex and of the medial subfield of the dorsal cortex; to the paraventricular zone of the inner plexiform layer of the medial cortex; and bilaterally to the dorsal part of the dorsal precommissural septum. Thedorsal part ofthe intermediate and caudal medial cortex and theventralmost folded part of its caudal edgeproject rostrally to the juxtasomatic zone of the outer plexiform layer and the entire inner plexiform layer of the intermediate and lateral subfields of the dorsal cortex and to the ventral part of the dorsal septum. In its intense Timm reaction and its ultrastructural properties, as reported in earlier studies, the Timm‐positive fiber system of the lizard brain shows a close resemblance to the mossy fiber system of the mammalian hipp

ISSN:0092-7317    

DOI:10.1002/cne.902760402

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

年代:1988

数据来源: WILEY

摘要:

AbstractPrevious studies have described the distribution of serotonin‐ and enkephalin‐immunoreactive elements in the posterior lobe vermis of the oposum's cerebellum. In the present study we have used a double labeling paradigm which combines the retrograde transport of horseradish peroxidase (HRP) with serotonin and enkephalin immunohistochemistry to determine the brainstem origin of serotoninergic and enkephalinergic neurons that project to the opossum's cerebellar cortex.Subsequent to HRP injections into the posterior lobe vermis, widespread areas of the medulla and pons were found to contain retrogradely labeled neurons. Serotonin‐immunoreactive somata are present primarily in the raphe nuclei and the adjacent reticular formation. Enkephalinergic neurons were numerous in the raphe nuclei, medial accessory olive, gigantocellular reticular formation, locus coeruleus, and the nucleus of the trapezoid body. However, serotoninergic neurons that project to the cerebellum were located only in the medullary pyramids and the reticular formation adjacent to the raphe. Double‐labeled enkephalinergic neurons were located 1) within the medullary pyramids, 2) throughout the extent of the caudal medial accessory olive, 3) in the rostral subnucleus a of the medial accessory olive, 4) in the nucleus reticularis gigantocellularis pars ventralis, 5) in the nucleus reticularis lateralis, and 6) in the nucleus reticularis ventralis lateral to the inferior olivary complex.These results indicate that although neurons containing serotonin and enkephalin immunoreactivity may be present in some of the same pontine and medullary nuclei, those serotoninergic and enkephalinergic neurons that project to the cerebellum are present primarily in restricted and spatially separate regions of the caudal

ISSN:0092-7317    

DOI:10.1002/cne.902760403

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

年代:1988

数据来源: WILEY

摘要:

AbstractNeurulation, formation of the neural tube, is a complex process involving shaping and bending of the neural plate and closure of the neural groove. We have used avian embryos as model systems to study this process. In the present investigation, blastoderms were cut parasagittally through their entire thickness, either unilaterally or bilaterally, at two mediolateral locations: (1) at the juncture between prospective neural plate and prospective surface epithelium, and (2) at the juncture between the midline strip of prospective neural plate and more lateral prospective neural plate. In the first experiment, shaping of the neural plate seemed normal, but elevation and convergence of the neural folds and closure of the neural groove were inhibited (except at the forebrain level). This result demonstrates that extrinsic forces generated by lateral tissues are required for neural plate bending and neural groove closure. In the second experiment, neuroepithelial cells within the isolated, midline strip became wedge shaped. This result indicates that neuroepithelial cell “wedging” is an active event occurring independently of forces generated by elevation of the neural folds. Additional studies are required to define the natures of neurulation forces and the mechanisms by which they are genera

ISSN:0092-7317    

DOI:10.1002/cne.902760404

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

年代:1988

数据来源: WILEY

摘要:

AbstractPH‐8P (dynorphin[1–8])‐like immunoreactive neuronal perikarya, processes, and terminals located within the human hypothalamus were investigated by the avidin‐biotin peroxidase complex (ABC) immunocytochemical procedure. Immunopositive neurons were distributed throughout the hypothalamus. The distributional pattern was found to be similar to that in other mammalian species by the use of antisera against dynorphin. A large number of immunoreactive neuronal perikarya were detected in the supraoptic nucleus (SON) and the magnocellular portion of the paraventricular nucleus (PVN). Their processes appeared to project to the posterior pituitary via the internal layer of the median eminence and their distribution seemed to be less dense than in other mammalian species. PH‐8P and vasopressin were colocalized in the neuronal perikarya in the human SON unlike the colocalization of these peptides in the rat SON and PVN. There were a few immunoreactive terminals in the external layer of the median eminence; their immunoreactive substances may be released into the portal veins to act on anterior pituitary cells. In addition, PH‐8P‐like immunoreactive neurons in the human hypothalamus may project to the extrahypo

ISSN:0092-7317    

DOI:10.1002/cne.902760405

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe distribution of histamine‐immunoreactivity in the carbodiimide‐fixed brain and visual system of the cockroach was revealed immunocytochemically with an antiserum against histamine (HA). Histamine levels were measured with high‐pressure liquid chromatography. The results show a widespread distribution of histamine‐containing somata and fibers in the brain, particularly in the visual system. The most intense immunolabeling was seen in the retinal photoreceptors and in the first optic ganglion, the lamina, where the short visual fibers make synaptic connections with the monopolar neurons, which also displayed immunofluorescence. Immunoreactive long visual fibers traversed the lamina and outer chiasma, terminating in the distal medulla. Tracts of histamine‐immunopositive fibers appeared to link the optic ganglia to the protocerebrum. Prominent histamine‐containing neurons were situated in the lateral protocerebrum. Immunolabeled pathways consisting of large‐diameter fibers also were seen in the cockroach brain. The central parts of the brain, including the central body, were reached by thick immunoreactive fibers that gave rise to intensely fluorescent varicose processes there. In the mushroom bodies, immunoreactivity was limited to the calyces. The protocerebral bridge was nonreactive. Immunofluorescence was seen also in the antennal lobes, but not in the antennal nerves. The biochemical measurements correlated well with the immunocytochemical data. The retinas and optic lobes, measured together, contained remarkably large amounts of histamine. These results reinforce the hypothesis presented by Hardie ('87) and Elias and Evans ('83) that histamine functions as a neurotransmitter in the photoreceptors of some, if not all, i

ISSN:0092-7317    

DOI:10.1002/cne.902760406

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe present paper is concerned with the arrangement of axons and synaptic terminals immunostained for calcitonin gene‐related peptide (CGRP), a primary afferent marker, in the primate (Macaca fascicularis) dorsal horn. The CGRP axons and terminals are uniformly distributed in laminae I and II outer (o) but they are concentrated laterally and distributed intermittently in the reticulated region of lamina V. A prominent bundle of labeled axons is seen in the sacral cord dorsal to the central canal. Emphasis is given to the relation of CGRP‐immunoreactive terminals to other terminals, both labeled and unlabeled, in laminae I and IIo. In this regard, adjacent CGRP‐immunoreactive terminals are often united by puncta adhaerentia. Of particular interest is the observation that CGRP‐immunoreactive terminals can be found presynaptic to other terminals which sometimes resemble central primary afferent endings. In addition CGRP‐immunoreactive terminals end on other CGRP terminals. Both findings suggest that primary afferent terminals interact synaptically with other primary afferent

ISSN:0092-7317    

DOI:10.1002/cne.902760407

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

年代:1988

数据来源: WILEY

摘要:

AbstractCochlear nerve morphology was examined in a series of rats ranging in age from young adulthood to advanced age in order to assess the extent of fiber loss and the nature of degenerative changes with age. The animals were perfused via the aorta with mixed aldehydes. Blocks including the cochlear nerves were removed, embedded in Araldite, and sectioned in a plane transverse to the longitudinal axis of the nerve. Analysis of the material included counts of normal and degenerating fibers and of glial cells, maps of fiber packing densities, and measurements of the cross‐sectional area of the nerve.The median number of normal fibers in the young adult animals (2‐3 months) was 21,218. This number was reduced by 21% at 26.5 months and by 24% in the oldest group (35‐36 months). The number of degenerating myelin sheaths was first seen to be significantly increased at 6 months, reached a peak at 26.5 months, and declined at 35‐36 months. There was an age‐related increase in the cross‐sectional area of the nerve, amounting to about 60% at 26.5 months and to about 50% at 35–36 months. Fiber packing density decreased evenly with age over the area of the nerve. The increased cross‐sectional area and decreased fiber packing density appeared to be related to increases in the thickness of myelin sheaths and in the area occupied by inter

ISSN:0092-7317    

DOI:10.1002/cne.902760408

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis study provides a scheme for subdividing the nucleus of the solitary tract of the hamster on the basis of cytoarchitectonic criteria, cell measurements, and neuronal cell types identified with the Golgi method. Reduced silver‐stained sections revealed the feltlike neuropil that characterizes the nucleus of the solitary tract and were used to define the boundaries of the nuclear complex. Adjacent sections stained for Nissl substance revealed ten subdivisions, each with a characteristic neuronal architecture based on cell sizes, shapes, and packing density. Some subdivisions, e.g., the ventral and medial subnuclei, were identified at all rostrocaudal levels of the nuclear complex, while other subdivisions, e.g., the caudally located dorsolateral and ventrolateral subnuclei, were restricted to particular levels. Golgi preparations were counterstained for Nissl substance, thus allowing dendro‐ and cytoarchitecture to be compared directly. This material permitted the identification of a number of functionally relevant features of the neuronal constituents of the subdivisions. This approach, employing three cytological methods, has permitted the assembly of a detailed atlas of the nucleus of the solitary tract. The subdivisions of the present atlas have been compared with their likely counterparts identified in previous investigations of the mammalian nucleus of the solitary tract. In order to relate cytoarchitecture with primary afferent termination sites and to define the gustatory‐recipient subdivisions, the differential relationships of the subdivisions with lingual afferent projections in the hamster are also described. The present parcellation scheme is intended to facilitate anatomical and physiological investigations of the types of circuits that compose the medullary gustatory and general visceral sensory sy

ISSN:0092-7317    

DOI:10.1002/cne.902760409

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe auditory receptor of the red‐eared turtle has been the subject of intensive electrophysiological study within the last decade, yet the details of its ultrastructure have remained uninvestigated. In the present report information is derived from an analysis of specimens prepared for light, scanning electron, and transmission electron microscopy. Attention is focused on the ultrastructure of hair cells, supporting cells, and nerve fibers within the sensory epithelium as well as the basilar membrane upon which it rests. A description of the receptor's relations to surrounding sensory epithelia, the limbus of the cochlear duct, and the basilar membrane is also included. Observations are discussed in the light of similar information from other reptilian auditory receptors and the mammalian organ of Cort

ISSN:0092-7317    

DOI:10.1002/cne.902760410

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

年代:1988

数据来源: WILEY

摘要:

AbstractInnervation patterns in the auditory receptor of the red‐eared turtle were reconstructed from serial ultrathin sections. Four locations were studied, including three on the basilar membrane and one on the basal limbus. In that area of the papilla located above the apical end of the basilar membrane most cells were innervated by single afferent fibers which, in turn, supplied as many as three cells. Although afferents in the midmembrane area of the papilla supplied fewer cells, the innervation pattern was similar in other respects to that in the apical area including an abundance of efferent synapses on afferents. In contrast, hair cells in the basal membrane area were contacted by two afferent fibers and had five times as many afferent synapses as observed previously. Here, each afferent made twice as many synapses as fibers in the previous two areas and supplied one or two hair cells but received no efferent synapses. In the basal limbus area, each hair cell was contacted by as many as eight afferents and each afferent supplied as many as seven hair cells. The significance of these innervation patterns is discussed in the light of structural information obtained from other vertebrate auditory receptors and in the light of available functional information derived from the turtle papill

ISSN:0092-7317    

DOI:10.1002/cne.902760411

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

年代:1988

数据来源: WILEY