摘要:

AbstractThe aim of this work was to study the ultrastructural distribution of substance P–like immunoreactivity in laminae I and II of rat spinal cord and trigeminal subnucleus caudalis in relation to synaptic glomeruli. A bispecific monoclonal antibody directed against substance P and horseradish peroxidase was used, combining sensitive immunocytochemistry with preservation of fine ultrastructural detail. Some of the quantitative observations were carried out with an automated image analysis system.The study revealed that in lamina I of the spinal cord, almost all immunoreactive profiles counted were nonglomerular, and a considerable number of them contacted medium‐size or large dendrites or were in direct contact with other vesicle‐containing profiles. In ventral lamina II, 9.4% of the labeled axonal varicosities were central boutons of type I glomeruli (CI). They could be identified by their scalloped contour, number and types of peripheral profiles, reduced density of mitochondria, and localization in the dorsal horn. However, these immunoreactive glomerular CIboutons (14.1% of the total number of CI) differed statistically from the prevailing population of nonimmunoreactive CI, by being surrounded by less peripheral neuronal profiles, which established fewer synapses. In addition, they contained more than three dense‐core vesicles per central profile.In the trigeminal subnucleus caudalis laminae I and II, the substance P fibers and varicosities had a plexiform orientation at the light microscopic level, which contrasted with the mainly rostrocaudal orientation of the spinal cord's lamina II plexus. However, the main ultrastructural findings were similar.These results demonstrate that substance P–like immunoreactivity occurs in a large number of type I synaptic glomeruli with specific morphological features and reinforce the current concept that the substantia gelatinosa of the spinal cord and trigeminal subnucleus caudalis are homologous s

ISSN:0092-7317    

DOI:10.1002/cne.902810402

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

年代:1989

数据来源: WILEY

摘要:

AbstractUptake of3H‐serotonin followed by autoradiography, and uptake of the serotonin analog 5,7‐dihydroxytryptamine (5,7‐DHT), with subsequent staining, were each used to define a unique set of neurons in the retina of the African clawed frog,Xenopus laevis. Both techniques demonstrated the same population of neurons, on the basis of perikaryal size, shape, and position within the retina. Two classes of amacrine cells accumulated 5,7‐DHT at the proximal (vitread) margin of the inner nuclear layer; the two classes were distinguished by the size of their perikarya. Two similar populations of cells, observed in the ganglion cell layer with lower frequency, may represent “displaced” counterparts of these two amacrine cell types. A class of bipolar cells whose perikarya were located in middle‐to‐distal regions of the inner nuclear layer also accumulated 5,7‐DHT and3H‐serotonin. Processes of these cells contributed to a dense plexus of fine fibers that appeared evenly distributed throughout the inner plexiform layer.3H‐Serotonin‐accumulating cells first appeared in the developing retina at stage 35/36, a time immediately after retinal stratification but before elaboration of either plexiform layer. Electron microscopic analysis permitted an identification of3H‐serotonin‐accumulating terminals in the inner plexiform layer. Serotonin‐labeled terminals containing conventional contacts, suggestive of amacrine cells, were presynaptic to unidentified processes and postsynaptic to bipolar cells. Labeled terminals containing ribbon contacts, indicative of bipolar cells, were postsynaptic to amacrine cells. The amount of serotonin contained in isolated retinas was 15 pmol/mg protein as measured by HPLC with electrochemical detection. We attempted to stimulate the release of accumulated3H‐serotonin from mature retinas by increasing the K+‐concentration in the bathing medium. Although preloaded glycine is readily released from14C‐glycine‐accumulating neurons, from the same retinas there was no calcium‐dependent, K+‐stimulated release of3H‐serotonin. This finding suggests that serotonin and glycine are processed differently by retinal neurons, the consequence of which

ISSN:0092-7317    

DOI:10.1002/cne.902810403

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe present study, using a combination of catecholamine (CA) histofluorescence and peptide immunocytochemistry in the same tissue sections, investigated the coexistence of neuropeptide Y (NPY) and methionine‐enkephalin‐Arg6‐Gly7‐Leu8(MEAGL)‐like immunoreactivity (LI) in catecholaminergic neurons of colchicine‐treated rat brain stems. Of the total number of catecholaminergic neurons in the A1/C1, A2/C2, A3, A4, and A6 regions approximately 83, 28, 98, 76, and 36%, respectively, contained both NPY‐LI and CA. Of the total number of catecholaminergic neurons in A1/C1, A2/C2, A3, and A5 regions, approximately 47, 4, 8, and 17%, respectively, contained both MEAGL‐LI and CA. Moreover, about 24% of the catecholaminergic neurons in the A1/C1 region contained both NPY‐ and MEAGL‐LI. Neither the noradrenergic neurons (A7) in the pons nor any of the dopaminergic neurons in the midbrain (A8, A9, A10) contained NPY‐ or MEAGL‐LI. Neurons containing both NPY‐ and MEAGL‐like immunoreactive peptides without CA were not found in the rat brain stem.These findings indicate that catecholaminergic neurons in the brain stem of the rat can be subdivided into distinct subgroups on the basis of the coexi

ISSN:0092-7317    

DOI:10.1002/cne.902810404

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe central nucleus of the barn owl's inferior colliculus (ICc) contains a representation of both the ipsilateral and contralateral auditory hemifields. The representation of ipsilateral space is found in the “core” of the ICc, a subdivision defined by the terminal field of nucleus laminaris, the avian analogue of the medial superior olivary nucleus. The representation of contralateral space is found in the lateral portion of the “shell” of the ICc. The shell surrounds the core and is defined by the terminal field of the nucleus angularis, one of the cochlear nuclei. The representation of ipsilateral space in the core of the ICc may be accounted for by the crossed projection from the nucleus laminaris because most of the nucleus laminaris is devoted to a representation of contralateral space.We present evidence to suggest that the representation of contralateral space is due to a commissural projection from the core of one side to the lateral shell of the opposite side. Injection of horseradish peroxidase (HRP) into the lateral portion of the ICc shell produced retrogradely labeled somata in the core of the opposite side. Injection of tritiated proline into the core produced anterograde label confined to the lateral shell, thus confirming the observations made with HRP. Thus, for example, the left ICc core, which contains predominantly a representation of the left hemifield, innervates the right lateral shell, endowing it with a representation of the left, or contralateral hemifield. The representation of contralateral space in the lateral shell is ultimately conveyed to the external nucleus of the inferior colliculus where it contributes the horizontal axis to a two‐dimensional map

ISSN:0092-7317    

DOI:10.1002/cne.902810405

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe morphology and frequency of axosomatic contacts on three functionally identified primate spinothalamic tract (STT) cells were analyzed at the electron microscopic level. The STT cells analyzed were wide‐dynamic‐range neurons responsive to activation of low‐ and high‐threshold cutaneous afferents innervating the foot. The somas were located in the lateral border of lamina V; the dendritic trees were oriented dorsally and were very extensive. Numerous spinelike appendages were observed emanating from two of the cell bodies. Terminal types contacting the cell bodies were categorized at several different layers through each neuron. Six morphologically different terminal types were established following analysis of serial sections. Profiles classified as round (R) terminals containing round clear vesicles and zero or one densecore vesicle made up over 50% of the total population in contact with the STT somas. Profiles containing round clear vesicles and two to four small‐diameter dense‐core vesicles (D1 category) made up approximately 10% of the population in contact with each soma. Flat (F) terminals with oblong or flattened clear vesicles made up approximately 8% of the population. The remaining three categories (D2, L1, and L2) distinguished by the number and size of the dense‐core vesicles made up a small percentage of the total population in contact with the cell bodies. The distribution of terminal types on the soma proper versus somatic spines was also determined for one cell. The proportions of the six terminal types contacting the soma of these cells were very similar, although the physiological characteristics of each cell were different. However, the relative proportions of terminal types on these three lamina V STT cell bodies were different from those previously reported contacting somata in lamina V, suggesting that there may be a unique innervation of STT cells that differentiates them from other cell type

ISSN:0092-7317    

DOI:10.1002/cne.902810406

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe interhemispheric and ipsilateral afferents of the superior temporal region (STR) were investigated with the aid of fluorescent retrograde tracers (Diamidino Yellow and Fast Blue). Different tracers were injected in selected cortical areas of the STR of each hemisphere of four rhesus monkeys. The results show that the interhemispheric afferents originate not only from the homotopic but also from heterotopic areas. The heterotopic areas giving rise to interhemispheric projections correspond to cortical areas of the origin of the ipsilateral projections. Although there is considerable overlap of labeled neurons of both afferent systems, only occasional double‐labeled neurons are found. Whereas the laminar patterns of ipsilateral neurons of origin vary considerably, the interhemispheric projection neurons are located mainly in cortical layer III.This study provides additional information about the ipsilateral connectional organization of the superior temporal region. That is, the primary auditory area receives projections not only from adjacent lateral and medial cortical regions but also from adjoining rostral and caudal cortical regions. Thus, the highly differentiated primary auditory cortical area receives strong projections from the surrounding less‐differentiated cortical regions. This connectional pattern is discussed from the perspective of the growth ring concept of cortical developm

ISSN:0092-7317    

DOI:10.1002/cne.902810407

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe neurogenetic gradients of neurons showing glutamic acid decarboxylase (GAD) immunoreactivity were determined in the regio superior and in the regio inferior of the mouse hippocampus. Pregnant C57B1 mice received pulse injections of (3H)thymidine from E11 through E17 (E0 being the day of mating). Distributions of (3H)thymidine‐labeled, GAD‐positive neurons in the different strata of the hippocampus proper were recorded in adult animals. GAD‐positive neurons in this region are generated prenatally. Radial gradients of neurogenesis of GAD‐positive cells are characterized by two main features: (1) with the exception of the stratum lacunosum‐moleculare and its interface with the stratum radiatum, GAD‐positive neurons of the plexiform strata are generated before those destined for the pyramidal layer; (2) within the pyramidal layer, GAD‐positive cells are positioned according to an inside‐out sequence. In the transverse axis, neurogenesis of GAD‐positive cells follows a regio inferior to regio superior gradient. This gradient is due to prolonged neurogenesis of GAD‐positive cells for the pyramidal layer in the regio superior. Given the selective laminar disposition of the GABAergic interneurons in the hippocampus, the present authors explored whether or not the diverse types of these interneurons could have specific birth dates and concluded that no relationship exists between birth dates and adult phenotypes of GAD‐immunoreactive cells in the mou

ISSN:0092-7317    

DOI:10.1002/cne.902810408

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe temporal patterns of neurogenesis of cells showing glutamic acid decarboxylase (GAD) immunoreactivity were determined in the area dentata of the mouse. Pregnant C57Bl mice received pulse injections of (3H)thymidine from E11 through E17 (E0 being the day of mating). The distribution of (3H)thymidine‐labeled, GAD‐positive neurons in the hilus and in the different strata of the fascia dentata (stratum infragranulosum, stratum granulosum, stratum moleculare) were recorded in adult animals. A radial gradient of neurogenesis of GAD‐positive cells in the area dentata was not apparent. In the transverse axis, neurogenesis of GAD‐positive cells seemed to follow a faint suprapyramidal to infrapyramidal gradient, which was due to differential timing of neurogenesis of GAD‐positive cells destined for the stratum infragranulosum of the suprapyramidal and infrapyramidal blades of the fascia dentata. GABAergic neurons in the fascia dentata comprise a limited number of welldefined cell types. All of the differet morphologic types of GAD‐positive neurons present in the area dentata were generated prenatally. These diverse forms did not have specific times of neurogenesis. These results support the concept that the adult morphology of GAD‐positive cells in the area dentata of the mouse do not bear any relationship to their ti

ISSN:0092-7317    

DOI:10.1002/cne.902810409

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe morphological organization of inputs from restricted sectors of the cat cochlear spiral ganglion into the cochlear nucleus was studied by making focal extracellular injections of horseradish peroxidase (HRP) into the spiral ganglion. Injections resulted in Golgi‐like labeling of a small cluster of spiral ganglion cells and their peripheral and central axons.Large injections involved most of the cells within Rosenthal's canal in sectors of the spiral ganglion innervating ≥;1 mm of the basilar membrane and resulted in narrow, complete laminae of labeled axons and preterminal fields within each cochlear nucleus subdivision. The positions of these bands were consistent with the “isofrequency laminae” appropriate for the frequencies represented at the injection sites, with high frequency laminae situated more dorsally, and lower frequencies progressively more ventral. A discrete projection to the small cell cap area was observed that was discontinuous with the main projection laminae in the ventral cochlear nuclei (VCN). In the dorsal cochlear nucleus, projecting fibers and terminals were excluded from the molecular cell layer. No labeled fibers entered the granule cell areas.In contrast to larger injections, very small HRP deposits labeled only part of an isofrequency lamina. Specifically, injections restricted to the scala tympani aspect of the spiral ganglion labeled only the lateral part of VCN isofrequency laminae, whereas injections limited to the scala vestibuli aspect of the ganglion labeled the medial aspect of the isofrequency planes. Thus these data indicate a previously unrecognized topographic representation of the vertical dimension of the spiral ganglion across VCN isofrequency laminae. Some posible functional implications of this projection organization are di

ISSN:0092-7317    

DOI:10.1002/cne.902810410

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe retinotectal projection in larval goldfish was studied with the aid of anterograde filling of optic fibers with HRP applied to the retina. The results show that optic fibers have already reached the tectum and begun to form terminal arbors in newly hatched fish. The projection is topographic in that fibers from local regions of the retina project to discrete patches of tectum, with the smallest patch covering 3.5% of the total surface area of tectal neuropil. Many fibers in young larvae have numerous short side branches along their length and only some of them show evidence of terminal sprouting. The arbors are approximately elliptical in shape and average about 1,500 μ;m2. Growth cones are seen frequently. In older Iarvae, terminal arbors are larger and more highly branched, and they have begun to resemble those in adult fish. Fibers terminate in two strata; those in the upper layer are smaller (1,800 μ;m2on average) than those in the deeper stratum (4,000 μ;m2on average). The fraction of tectal surface area covered by individual arbors (the “tectal coverage”) ranges from 1.5% to 3% of the total surface area of the tectal neuropil. In contrast, the tectal coverage of individual arbors in young adult goldfish is much smaller, ranging from 0.02% to 0.42% of tectal surface area (Stuermer, '84, and unpublished). This apparent increase in precision of the map in older animals is not due to retraction of arbors, which are slightly larger in adults, but is accounted for by overall tectal growth: the tectal neuropil in goldfish increases in area by about 250‐fold during this period (Raymo

ISSN:0092-7317    

DOI:10.1002/cne.902810411

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

年代:1989

数据来源: WILEY