摘要:

AbstractThe cell bodies of thoracolumbar sensory and sympathetic pre‐ and postganglionic neurons that project to the colon and pelvic organs of the male rat were labeled retrogradely with horseradish peroxidase (HRP) in order to study numbers, segmental distribution, and location of the somata of these neurons quantitatively. HRP was applied to one hypogastric nerve (HGN), to the lumbar colonic nerves (LCN) and to the intermesenteric nerve (IMN). In order to estimate the significance of the branching of one axon into both hypogastric nerves a double‐labeling technique with fluorogold and HRP was used.About 2640 neurons project into the two HGN added together (800 afferent, 1320 pre‐, and 520 postganglionic), 4650 neurons into the LCN (360 afferent, 0 pre‐ and 4290 postganglionic), and 5990 into the IMN (1500 afferent, 1250 pre‐, and 3240 postganglionic). About 4190 sympathetic postganglionic prevertebral neurons innervate the colon and pelvic organs, 1900 are located in the inferior mesenteric ganglion and 2290 in ganglia of the IMN. Considering the efferent component, the HGN mainly are preganglionic and the LCN exclusively postganglionic nerves. Branching of one axon into both HGN is a rare event and quantitatively negligible (<3%).Afferent neurons of all three nerves were found in the dorsal root ganglia (DRG) T12‐L2 with the maximum in L1 and L2. The distribution of afferent neurons projecting into the LCN is shifted slightly more rostrally compared to neurons projecting into the HGN. The IMN distribution is located in a position in between. Preganglionic neurons projecting into the IMN are located in the spinal cord segments T12‐L3 with the maximum in LI and L2. Sympathetic postganglionic paravertebral neurons of all three types of nerves are more widely distributed (T12‐L5). Neurons projecting into the LCN are shifted more caudally than those projecti

ISSN:0092-7317    

DOI:10.1002/cne.903140302

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe projections and terminal ramifications of electrophysiologically characterized myenteric neurons of the guinea pig small intestine were studied after intracellular injection of the marker substance biocytin. Myenteric neurons were impaled with microelectrodes containing 4% biocytin in 2 M KCl (pH 7.4) and characterized electrophysiologically as either AH‐neurons or S‐neurons. AH‐neurons were neurons in which action potentials were followed by prolonged after‐hyperpolarizations (lasting>4 seconds). S‐neurons were neurons in which such hyperpolarizations were not seen. Electrical stimulation of internodal strands evoked prominent fast excitatory synaptic potentials in S‐neurons, but not in AH‐neurons. Biocytin was injected electrophoretically into the impaled AH‐neurons by passage of hyperpolarizing current (0.6–0.8 nA for 5–15 minutes) through the recording electrode. The preparation was then fixed in Zamboni's fixative, dehydrated, and exposed to avidin coupled to horseradish peroxidase which allowed the injected biocytin to be visualised via a diaminobenzidine reaction. In many cases, the injected biocytin appeared to fill all the processes of injected AH‐neurons that ramified within the myenteric plexus. The filled processes included axons running up to 4 mm within the plexus and profuse varicose terminals ramifying within both the ganglion containing the injected cell body and nearby ganglia. Most (90%) cell bodies of the injected AH‐neurons had the morphology of Dogiel type II neurons; large, mostly smooth cell bodies with few short processes and several long processes. The other 10% of the AH‐neurons had similar cell bodies and long processes but also had prominent short filamentous processes. This population was termed dendritic AH‐neurons. The projections and terminals of 28 AH/Dogiel type II neurons and 7 dendritic AH‐neurons were analysed in detail. Both types of neurons project circumferentially to provide terminals to nearby ganglia, but the AH/Dogiel type II neurons also provide terminals to their own ganglia while the dendritic AH‐neurons typically do not. Although many of the injected AH‐neurons had projections orally or anally along the intestine no evidence for a preferential direction of projection was obtained. Analysis of the areas and distributions of the terminal fields of the AH/Dogiel type II neurons suggests that each may contact several other myenteric neurons and that each myenteric neuron may receive input from ab

ISSN:0092-7317    

DOI:10.1002/cne.903140303

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe topographical relationship between the swim bladder, the inner ear, and the otic lateral line was studied in the bottom dwelling catfish,Ancistrussp. In addition, afferent and efferent subcomponents of the eighth and lateral line nerves were labelled with horseradish peroxidase (HRP) or with differently fluorescing dextran amines.The swim bladder ofAncistrusconsists of two separate, transversely oriented parts each of which is connected to the sinus impar of the inner ears via two Weberian ossicles and the perilymphatic sac. The osseous capsula of the ear has two foramina other than the nerve foramina. One is for the sinus impar. The other foramen, which also separates two fluid‐filled spaces, exits where the horizontal canal of the ear contacts the otic lateral line.Both the otic and the postotic lateral line canal run deep below the epidermis. Each canal contains a neuromast that is innervated by the middle lateral line nerve. Further caudally, the otic lateral line canal gives rise to the postotic and finally to the trunk canal whose nonossified anterior part travels through an ossified chamber that surrounds the swim bladder. Thus the anterior part of each trunk lateral line canal is in contact with a bipartite sound pressure receiver, the swim bladder.Anterior and posterior lateral line afferents terminate ipsilaterally throughout the neuropil of the electroreceptive lateral line nucleus and the mechanoreceptive nuclei medialis and caudalis of the medulla. Middle lateral line afferents terminate between the projection sites of anterior and posterior lateral line afferents. Some primary mechanosensory anterior lateral line nerve fibers continue into the ipsilateral eminentia granularis and the valvula cerebelli, In the electroreceptive lateral line projection, anterior lateral line fibers terminate more medially and posterior fibers more laterally. This somatotopy is not as clear‐cut in the mechanosensory lateral line.Afferents of the sacculus and the lagena terminate predominantly in the saccular nucleus. Afferents of the utriculus, the horizontal canal, and the anterior vertical canal terminate in the magnocellular vestibular nucleus and in the medial octavolateral nucleus. The projection sites of the anterior part and the posterior part of the eighth nerve show little overlap. Eighth nerve projections to the valvula cerebelli are less prominent than the projections from the lateral line.Eighth nerve and lateral line nerve efferents arise from a common nucleus, the octavolateralis efferent nucleus. Axons of efferent cells may divide to supply two or more branches of the eighth nerve and some axons supply both lateral line and eighth nerve endorgans.The anatomical relationships between the head lateral line and the inner ear suggest that parts of the lateral line ofAncistrusparticipate in sound pressure perception. The assumed pressure sensitivity of the sacculus and the lagena probably is reflected in the distinct projection of saccular and lagena fibers to a definable auditory nucleus, the saccular nucleus. In contrast and irrespective of the supposed auditory function for parts of the head lateral line, no primary lateral line afferents were found to project to an acoustic or vestibular nucleus. Physiological studies are under way to find out whether and how the lateral line ofAncistrusis involved in sound pressure percept

ISSN:0092-7317    

DOI:10.1002/cne.903140304

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

年代:1991

数据来源: WILEY

摘要:

AbstractImmunoreactivity to four neurotransmitters/transmitter‐related enzymes was found in the dorsomedial telencephalon (hippocampal region) of the pigeon. Putative afferent fibers containing choline acetyltransferase‐like, serotonin‐like, and tyrosine hydroxylase‐like immunoreactivity were seen in a fiber tract passing through the septo‐hippocampal junction and along the medial wall of the hippocampal region. The most intensive labeling of neuropil and terminals of all four substances was found in the dorsomedial area of the hippocampal region. Glutamic acid decarboxylase‐like immunoreactivity was seen in sparsely scattered cells throughout the region. These results are discussed in relation to hypotheses about the boundaries and subdivisions of the hippocampal region of

ISSN:0092-7317    

DOI:10.1002/cne.903140305

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe distribution of six neuropeptides [substance P (SP), leucine (leu5‐) enkephalin (LANK), vasoactive intestinal polypeptide (VIP), cholecystokinin (CCK), neuropeptide Y (NPY), and somatostatin (SS)] in the dorsormedial telencephalon (hippocampal region) of the pigeon was studied by immunohistochemistry.All six peptides were found in fibers passing through the septo‐hippocampal junction and along the medial wall of the hippocampal region. NPY‐, SS‐, and VIP‐like staining of fibers was seen in the hippocampal commissure. NPY and SS had similar distributions within the hippocampal region, both being most conspicuous in cell bodies, terminals, and fibers of the medial hippocampal region. VIP‐positive cells were found in an area dorsal to the SS/NPY cell region. CCK‐like immunoreactivity was found in terminal baskets surrounding large cells of a v‐shaped structure in the ventromedial hippocampal region. SP‐ and LENK‐like immunoreactivity was found in neuropils in a lateral‐dorsal region, the two substances showing similar distributions. This region is thought to lie lateral to the limit of the hippocampal region.Parallels with the distribution of immunoreactivity in the mammalian hippocampus are used to suggest possible equivalent subdivisions of the avian and mammalia

ISSN:0092-7317    

DOI:10.1002/cne.903140306

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

年代:1991

数据来源: WILEY

摘要:

AbstractA comparative analysis of nicotinamide adenine dinucleotide phosphate (NADPH)‐diaphorase activity in the olfactory bulb was conducted in the hamster and rat. The distribution and morphological features of NADPH‐stained neurons were compared to those of glutamic acid decarboxylase‐like (GAD‐LI) and tyrosine hydroxylase‐like (TH‐LI) immunoreactive somata in order to relate NADPH‐staining to neuronal classes with specific biochemical properties.Intense NADPH‐staining was located in primary nerve fibers of the accessory and main olfactory systems, producing dense staining of individual glomeruli. The entire vomeronasal nerve and all glomeruli were stained in the accessory olfactory bulb, but olfactory nerve and glomerular staining were restricted to the dorsal half of the main olfactory bulb.The glomerular layer of the main olfactory bulb of both animals contained numerous small NADPH‐stained neurons. The range of somal areas of these neurons was relatively narrow and averaged about 60 μm2(ca. 8 × 11 μm). Most neurons possessed ovoid somata and monoglo‐merular intraglomerular dendrites. Previous Golgi studies indicate that such features characterize periglomerular cells. The somal areas of GAD‐LI somata in the glomerular layer overlapped that of the NADPH‐stained neurons, providing additional evidence that these neurons are probably periglomerular cells. The range of somal areas of TH‐LI somata in the glomerular layer was broader and included both small and large neurons that usually possessed intraglomerular dendritic tufts. The smaller TH‐LI somata corresponded in size to both the NADPH‐stained and GAD‐LI somata, suggesting an interrelationship among periglomerular cells, GAD‐LI, TH‐LI, and NADPH‐diaphorase activity. The larger TH‐LI somata were probably external tufted cells.In the external plexiform layer of the hamster, oriented NADPH‐stained neurons were observed that possessed an intraglomerular dendrite. These neurons appeared to be middle tufted cells. Lightly stained and smaller neurons were occasionally seen in the mitral body and internal plexiform layers, corresponding in somal area and morphological features to those of type III granule cells. No internal tufted or mitral cells were stained. The largest NADPH‐stained neurons were located in the inner half of the granule cell layer and were classified as Golgi cells. Their somata averaged 125 μm2(ca. 10 × 17 μm).Many NADPH‐stained neurons were observed in all subdivisions of the anterior olfactory nucleus, the anterior hippocampal rudiment, anterior and posterior levels of the piriform cortex, and the vertical and horizontal limbs of the diagonal band of Broca, all of which are known to provide centrifugal inputs to the olfactory bulb. However, fiber staining was restricted to the inner half of the granule cell layer, indicating limited central influences.In combination with immunocytochemistry, NADPH histochemistry has demonstrated stronger biochemical ties between periglomerular and external tufted cells than previously described, and points to possible shared physiological properties of periglomerul

ISSN:0092-7317    

DOI:10.1002/cne.903140307

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

年代:1991

数据来源: WILEY

摘要:

AbstractPrevious transneuronal anterograde tracing studies have shown that the retino‐thalamic pathway to the posteromedial lateral suprasylvian (PMLS) visual area of cortex is heavier than normal in adult cats that received neonatal damage to visual cortical areas 17, 18, and 19. In contrast, the strength of this projection does not appear to differ from that in normal animals in cats that experienced visual cortex damage as adults. In the present study, we used retrograde tracing methods to identify the thalamic cells that project to the PMLS cortex in adult cats that had received a lesion of visual cortex during infancy or adulthood. In five kittens, a unilateral visual cortex lesion was made on the day of birth, and horseradish peroxidase (HRP) was injected into the PMLS cortex of both hemispheres when the animals were 10.5 to 13 months old. For comparison, HRP was injected bilaterally into the PMLS cortex of three cats 6.5 to 13.5 months after they received a similar unilateral visual cortex lesion as adults. In cats with a neonatal lesion, retrograde labeling was found in the large neurons that survive in the otherwise degenerated layers A and A1 of the lateral geniculate nucleus (LGN) ipsilateral to the lesion. Retrograde labeling of A‐layer neurons was not seen in the undamaged hemisphere of these animals or in either hemisphere of animals that had received a lesion as adults. As in normal adult cats, retrograde labeling also was present in the C layers of the LGN, the medial interlaminar nucleus, the posterior nucleus of Rioch, the lateral posterior nucleus, and the pulvinar nucleus ipsilateral to a neonatal or adult lesion. Quantitative estimates indicate that the number of labeled cells is much larger than normal in the C layers of the LGN ipsilateral to a neonatal visual cortex lesion. Thus the results indicate that the heavier than normal projection from the thalamus to PMLS cortex that exists in adult cats after neonatal visual cortex damage arises, at least in part, from surviving LGN neurons in the A and C layers of the LGN. Although several thalamic nuclei, as well as the C layers of the LGN, continue to project to PMLS cortex after an adult visual cortex lesion, these projections appear not to be affected significantly by the les

ISSN:0092-7317    

DOI:10.1002/cne.903140308

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

年代:1991

数据来源: WILEY

摘要:

AbstractIn the study reported in the preceding paper, we used retrograde labeling methods to show that the enhanced projection from the thalamus to the posteromedial lateral suprasylvian (PMLS) visual area of cortex that is present in adult cats following neonatal visual cortex damage arises at least partly from surviving neurons in the dorsal lateral geniculate nucleus (LGN). In the C layers of the LGN, many more cells than normal are retrogradely labeled by horseradish peroxidase (HRP) injected into PMLS cortex ipsilateral to a visual cortex lesion. In addition, retrogradely labeled cells are found in the A layers, which normally have no projection to PMLS cortex in adult cats. The purpose of the present study was to investigate the mechanisms of this enhanced projection by examining the normal development of projections from the thalamus, especially the LGN, to PMLS cortex. Injections of HRP were made into PMLS cortex on the day of birth or at 1, 2, 4, or 8 weeks of age. Retrogradely labeled neurons were present in the lateral posterior nucleus, posterior nucleus of Rioch, pulvinar, and medial interlaminar nucleus, as well as in the LGN, at all ages studied. Within the LGN of the youngest kittens, a small number of retrogradely labeled cells was present in the interlaminar zones and among the cells in the A layers that border these zones. Such labeled cells were virtually absent by 8 weeks of age, and they are not found in normal adult cats. Sparse retrograde labeling of C‐layer neurons also was present in newborn kittens. The density of labeled C‐layer neurons increased 5‐ to 10‐fold between 1 day and 1 week of age and then increased further to adult values by 4 weeks of age. These results indicate that there is not an exuberant projection from the C layers of the LGN to the PMLS cortex in young kittens. This suggests, therefore, that the enhanced projection from the C layers to PMLS cortex after an early visual cortex lesion, described in the preceding paper, is due to new axonal growth. In contrast, at least part of the enhanced projection from the A layers after an early visual cortex lesion may result from the retention of an initially transient projection from the interlaminar zones and immediately adjacent cells in the A

ISSN:0092-7317    

DOI:10.1002/cne.903140309

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

年代:1991

数据来源: WILEY

摘要:

AbstractIn general, knowledge of the internal organization of receptive fields has played an important role in shaping current understanding of sensory physiology. Such knowledge is particularly important for understanding the function of the superior colliculus, since this structure is at once implicated in spatial localization and has relatively large receptive fields. While this issue has been addressed in the visual and auditory modalities represented in the superior colliculus, there are no previous studies of its somatosensory receptive field organization. Here, the properties of somatosendory receptive fields in the cat superior colliculus were studied quantitatively to determine whether they contain internal non‐homogeneities that might aid in the determination of stimulus detail. Of special interest was the possibility that these comparatively large receptive fields would contain areas of differential excitability that could aid in spatial resolution, that within‐field spatial summation and/or inhibition would be exhibited, and that the borders of the excitatory receptive field would be flanked by inhibitory regions. The data demonstrate that while inhibition beyond the receptive field borders is a rarity, these somatosensory receptive fields nearly always contain a well‐defined area of maximal sensitivity within which the size of the stimulus is a critical feature in determining the magnitude of the response. These best areas are systematically distributed across receptive fields as a function of their location in the structure, and indicate that the resolution of stimulus location and size may be greater than expected on the basis of receptive field size

ISSN:0092-7317    

DOI:10.1002/cne.903140310

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

年代:1991

数据来源: WILEY

摘要:

AbstractPrevious studies have revealed that polyribosomes are selectively localized beneath post‐synaptic sites on central nervous system (CNS) neurons, and are particularly prominent during periods of synapse growth. The present study evaluates whether polyribosomes are most prominent at a consistent time in the developmental history of the synapse, or instead at a consistent time in the life of the organism regardless of the state of synaptic maturation (suggesting a globally acting factor). We compare the time course of synaptogenesis and the association between polyribosomes and developing synapses in three regions that develop at different rates: the external and internal blades of the dentate gyrus, and the CA1 region of the hippocampus proper. Each region was examined electron microscopically at 1, 4, 7, 10, 15, 20, 28 and over 120 days of age, evaluating: (1) synapse density (the number of synaptic profiles/ area of neuropil), (2) the width of the neuropil layers, (3) the proportion of synapses with underlying polyribosomes, and (4) the number of polyribosome‐containing synapses/area of neuropil.As anticipated on the basis of the differences in cytogenesis, the time course of synaptogenesis was different in the three regions. In the external blade of the dentate gyrus, synapse density increased in a nearly linear fashion between birth and 15 days of age, and then continued to increase at a somewhat slower rate until 28 days of age. Synapse development in the internal blade was delayed by several days in comparison to the external blade. In CA1, synapse density increased slowly between 1 and 7 days, and then at a rapid rate between 7 and 28 days of age. In all three regions, the proportion of synapses with underlying polyribosomes was highest between 1 and 7 days of age, and then decreased as synapse density increased. However, the peak in the number of polyribosome‐containing synapses/unit area of neuropil occurred at different times in the three regions (4–7 days of age in the external blade of the dentate gyrus and in CA1, and 20 days of age in the internal blade). In addition to further defining the relationship between polyribosomes and developing synapses, the present study provides a data base on the time course of synapse development in the hippocampus and dentate gyrus, which will be useful for comparisons with other m

ISSN:0092-7317    

DOI:10.1002/cne.903140311

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

年代:1991

数据来源: WILEY