摘要:

AbstractThe olivocerebellar climbing fiber system was investigated in the rat with anterograde Phaseclus vulgaris leucoagglutinin (PHA‐L) tracing. The specific objective of the study was to find morphological evidence of climbing fiber collaterals innervating the cerebellar nuclei.Small iontophoretic injections of PHA‐L were placed in different parts of the inferior olivary complex, and labelled olivocerebellar fibers could be traced to their termination as climbing fibers in sagittal zones of the contralateral cerebellar cortex. Reaching the cerebellum via the restiform body, the labelled olivocerebellar axons entered the deep cerebellar white matter anterior to the cerebellar nuclei. Most of these thicker, nonterminal axons continued dorsally around the nuclei, but some ran through them. Bundles of fibers could be followed into the folial white matter toward their cortical zones of termination.Depending on which part of the olivary complex that was injected with PHA‐L, labelled axons were seen to converge on different regions of the cerebellar nuclei, where dense plexuses of thin varicose terminal fibers appeared. Quantitative estimates of the innervation ranged from 1.7 to 4.3 million boutons per mm3in the fastigial (FN), interposed, and main parts of the lateral cerebellar (LCN) nuclei, whereas the parvicellular portion of LCN demonstrated 15–20 million varicosities per mm3. Frequently, thicker olivocerebellar axons, which seemed directed toward the cerebellar cortex, were seen to send a fine collateral branch toward these areas of nuclear innervation.As controls, PHA‐L was injected into the degenerated olivary complex of 3‐acetylpyridine‐treated rats. Neither cortical climbing fiber terminals nor nerve terminal plexuses in the nuclei appeared in these experiments. In cases with injection sites extending into the reticular formation, substantial mossy fiber labelling was present bilaterally in the cortex, but the cerebellar nuclei were devoid of labelled innervation or demonstrated only a few larger diameter fibers.The projection of the inferior olivary complex to the cerebellar nuclei was strictly topographically organized and agreed in principle with the organization described in the cat by Groenewegen et al. ('79). The caudal medial accessory olive (MAO) projected to FN, the rostral MAO to the posterior interposed nucleus (NIP), the rostral part of the dorsal accessory olive (DAO) to the anterior interposed nucleus (NIA), and the principal olive (PO) to LCN. Smaller injections into olivary subnuclei resulted in labelled innervation in restricted sectors of individual cerebellar nuclei, suggesting the existence of a more detailed topographical

ISSN:0092-7317    

DOI:10.1002/cne.902880102

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe cerebellar projections of spinal border cells, which give rise to crossed ascending axons, were studied in the lower lumbar segments by the anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP) in the cat. Prior to the injections, the spinal cord was lesioned rostral and ipsilateral to the WGA‐HRP injections to eliminate labeling of the ipsilaterally ascending axons.Following injections of WGA‐HRP into the L4‐L6 segments, labeled terminals were seen in sublobules Ib‐Vf of the anterior lobe, sublobules VIf‐VIe, lobule VIII, the paramedian lobule, and crus II. More than 90% of the total number of labeled terminals were in the anterior lobe; the projections were predominantly ipsilateral to their cells of origin (about 90% or more labeled terminals of the total number in each of sublobules IIb‐Va). Many labeled terminals were seen ipsilaterally in sublobules IIb (11.1–17.5% of the total number), IIIa (11.7–12.9%), IIIb (16.1–17.6%), IVa (8.8–10.8%), IVb (6.2–10.5%), and Va (9.7–10.3%). In the posterior lobe, labeled terminals were numerous only in sublobule C of the ipsilateral paramedian lobule (2.7–4.9%).The projection fields in the horizontal plane of the lobules were reconstructed from a series of cross‐sections through each lobule. In the anteriorlobe, labeled terminals were distributed in four major areas. In sublobules IIa–IVa, area 1 was located between 1.0 and 2.0 mm lateral to the midline in zones B–C1 of Voogd; area 2, between 2.0 and 3.0 mm lateral to the midline in zones C1–C2; area 3, between 3.0 and 4.0 mm in zones C2–C3; and area 4, lateral to 4.0 mm from the midline in zone C3. These areas extended apicobasally in the apical to middle parts of the lobules. On the rostral side of sublobule C1 of the ipsilateral paramedian lobule, the projection areas extended in the entire apicobasal and the mediolateral axis of the sublobule, except in the most lateral part. The present results suggest that the SBCs project to spe

ISSN:0092-7317    

DOI:10.1002/cne.902880103

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

年代:1989

数据来源: WILEY

摘要:

AbstractWe studied the relationship of isthmotectal input to other tectal afferent fiber systems in three ways. (1) Using horseradish peroxidase (HRP) histochemistry, we determined the nonretinal inputs to the superficial tectum. In different sets of animals we (a) applied HRP to the tectal surface; (b) inserted HRP crystals into the tectum; (c) injected small volumes of HRP solutions into the superficial tectum. N. isthmi accounts for more than 65% of the nonretinal extrinsic input in the superficial tectal layers. One set of fibers from the contralateral n. isthmi projects to the most superficial layer. Fibers from posterior thalamus and tegmentum project to both superficial and deeper layers in the tectum, but not to the most superficial layer. The ipsilaterally projecting isthmotectal fibers terminate in the deeper superficial layers. (2) We investigated the relationship between retinofugal and contralaterally projecting isthmotectal pathways. We orthogradely labelled n. isthmi fibers by unilateral HRP injections into n. isthmi, and we also labelled retinal fibers by injecting tritiated 1‐proline into both eyes. In such animals contralaterally projecting isthmotectal fibers cross in the dorsal posterior region of the optic chiasm. From the chiasm to the tectum isthmotectal fibers and retinofugal fibers are admixed. (3) We determined whether other fiber systems cross with contralaterally projecting isthmotectal fibers. We cut the posterior part of the optic chiasm and applied HRP crystals to the cut. Only n. isthmi and retina are retrogradely labelle

ISSN:0092-7317    

DOI:10.1002/cne.902880104

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

年代:1989

数据来源: WILEY

摘要:

AbstractMetabolic labeling studies have shown that the developing hamster retinotectal pathway is marked by a high level of synthesis and axonal transport of the neuron‐specific phosphoprotein GAP‐43, which then decline sharply with synaptic maturation. To understand better the relationship of GAP‐43 to specific developmental events, we used a monospecific antibody to examine the location of this protein in the optic tract and retinal target areas at various stages. In late embryonic and in neonatal hamsters, dense GAP‐43 immunostaining was seen along the entire extent of the optic tract axons, including fascicles coursing over and through the lateral geniculate body (LGB) and within the upper layers of the superior colliculus (SC). The retinal origin of many of these fascicles was confirmed by their rapid disappearance after removal of the contralateral eye. During the first postnatal week, immunostaining in the fiber fascicles showed a marked decline, though the protein was still present throughout the neuropil of the LGB and SC. In the second postnatal week, the neuropil staining also diminished, and by 12 days after birth, both structures showed only light immunoreactivity. The high levels of GAP‐43 in embryonic and neonatal optic tract axons coincide temporally with axon elongation, initial target contact, and collateral formation by the retinofugal fibers, whereas subsequent concentration of the protein in the neuropil suggests its involvement in the elaboration of terminal arbors and synap

ISSN:0092-7317    

DOI:10.1002/cne.902880105

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

年代:1989

数据来源: WILEY

摘要:

AbstractA monoamine‐accumulating ganglion cell type has been identified in an in vitro preparation of the cat's retina by a catecholamine‐like fluorescence that appears following intravitreal injections of dopamine and the indoleaminergic transmitter analog, 5,7‐dihydroxytryptamine (5,7‐DHT). A subpopulation of large, weakly fluorescing neurons were identified as composing a single, morphologically distinct ganglion cell type by intracellular injections of horseradish peroxidase (HRP). In a sample of 374 HRP‐filled cells soma diameter ranged from 13–21 μm (mean ± SD = 16.6 ± 1.3). Dendritic field size increased with increasing retinal eccentricity from 150–200 μm diameter at 0.5 mm from the area centralis to 600–800 μm diameter in the far retinal periphery. Dendrites are thin (∼1 μm diameter), show a characteristic branching pattern, and are narrowly stratified at the outer border of the inner plexiform layer. The monoamine‐accumulating ganglion cell and the outer (OFF‐center) alpha cell occupy distinct strata within sublamina a of the inner plexiform layer separated by a gap of about 5 μm.The total number of monoamine‐accumulating (MA) ganglion cells was estimated at 5,400, about 3.5% of the total ganglion cell population. Spatial density of the MA ganglion cells, calculated from cell counts made in vitro, ranges from 60 cells/mm2near the area centralis to 5 cells/mm2in the far retinal periphery. A coverage factor (density x dendritic field area) of 2.2 was maintained from central to peripheral retina. The nature of the dendritic overlap was observed directly by making HRP injections into several neighboring ganglion cells. Five to seven neighboring dendritic trees extensively overlapped a given cell's dendritic field. However the dendritic processes did not intersect randomly but tended to interdigitate such that a uniform interdendritic spacing and density of dendritic processes was constructed locally within the dendritic plexus. Rotation of individual dendritic trees from their normal orientation produced a dramatic 4‐5‐fold increase in the number of dendritic intersections, suggesting that an active, local mechanism operates in the precise placement of individual dendrites within the plexus.The monoamine‐accumulating ganglion cell appears morphologically equivalent to the delta ganglion cell (Boycott and Wässle;J. Physiol. (Lond.)240: 397–419, '74; Kolb et al.;Vision Res.21: 1081–1114, '81) and to the recently recognized indoleamine‐accumulating ganglion cell (Wässle et al:J. Neurosci.7: 1574–1585, '87). Comparisons with previous studies indicate that they may be physiologically equivalent to the OFF‐center, sluggish sustained cells (also known as tonic W cells and Q cells) and probably project to the superior colliculus and/or the C

ISSN:0092-7317    

DOI:10.1002/cne.902880106

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

年代:1989

数据来源: WILEY

摘要:

AbstractLeucine enkephalin immunoreactivity was identified in axons and varicosities in parasympathetic ganglia located in the pelvic plexus and on the surface of the urinary bladder of the cat. Electron microscopic immunohistochemical studies revealed that varicosities containing leucine enkephalin exhibited large dense core vesicles and small, clear, spherical vesicles, which were similar to those found in cholinergic terminals. Leucine enkephalin immunoreactivity was primarily associated with large dense core vesicles. The varicosities formed axodendritic and axosomatic synapses with principal ganglion cells. Axoaxonic synapses were not detected. Some axosomatic enkephalinergic synapses were detected embedded within or invaginating the principal ganglion cells. Varicosities containing flattened and/or small dense core vesicles did not exhibit enkephalin immunoreactivity.Bladder ganglion cells identified by retrograde HRP tracing from the urinary bladder exhibited similar leucine enkephalinergic synapses. These observations, coupled with previous reports that leucine enkephalin is present in sacral preganglionc neurons and released by preganglionic nerve stimulation, suggest that leucine enkephalin and acetylcholine are cotransmitters stored and released from the same nerve terminals in bladder parasympahtitic ganglia.

ISSN:0092-7317    

DOI:10.1002/cne.902880107

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

年代:1989

数据来源: WILEY

摘要:

AbstractIn order to investigate the expression of cell adhesion molecules in synapses, we have studied the localization of the neural cell adhesion molecule N‐CAM in the cerebellum and hippocampus of adult mice by immunocytological and immunochemical methods. Of the three molecular components of N‐CAM with relative molecular masses (Mr) of 120, 140, and 180 kD, N‐CAM 120 is not detectable in synaptosomal membranes, whereas N‐CAM 140 is expressed on both pre‐ and postsynaptic membranes and N‐CAM 180 is restricted to postsynaptic sites, with localization of the N‐CAM 180‐specific epitope in postsynaptic densities. Specificity of immunoreactivity is indicated by the observation that antibodies to the neural cell adhesion molecule L1 do not label synaptic membranes, whereas antibodies to two major components of postsynaptic densities, actin and erythrocyte spectrin, react with synaptic structures. Interestingly, N‐CAM 180 is only detectable in subpopulations of synapses in the intact tissue. Isolated synaptosomes, opened for unimpeded accessibility of antibody by hypoosmotic treatment, also reveal a partial expression of N‐CAM 180 in that 67% are labeled by antibodies to N‐CAM 180, while antibodies to actin and erythrocyte spectrin react with 95% and 88% of all synaptosomes, respectively. N‐CAM 180 does not appear to be differentially expressed in synapses of a particular morphological type, but is detectable in all types of synapses in the cerebellum and hippocampus, except for mossy fiber synapses and synapses between basket and Purkinje cells, which are generally N‐CAM 180‐negative. Since N‐CAM 180 has been shown to be characteristic of stabilized or stabilizing cell contacts, possibly by its association with the cytoskeleton‐membrane linker protein spectrin (Pollerberg et al.:J. Cell Biol.101: 1921–1929, '85;Nature324: 462–465, '86;Cell Tissue Res.250: 227–236, '87), we would like to suggest N‐CAM 180 plays an important role in determining the stability of contacts between pre‐ and postsynaptic

ISSN:0092-7317    

DOI:10.1002/cne.902880108

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe development of cholinergic neurons in the mouse forebrain was studied by immunocytochemistry with a monoclonal antibody to choline acetyl‐transferase (ChAT), the rate‐limiting enzyme for acetylcholine synthesis. Since this antibody stained dividing cells in ventricular germinal zones as well as differentiating neurons, likely routes of migration could be inferred on the basis of the location of immunoreactive (IR) cells at different gestational ages. Germinal zones for cholinergic cells were observed in all ventricular zones of the forebrain with the ventral zones generating the earliest cells by gestational day 13.5 (GD13.5). On GD14, ChAT IR cells were visible in the germinal zones of the eye, olfactory ventricle, anterior horn, and dorsolateral aspect of the lateral ventricle, lateral ganglionic eminence, ventro‐ and dorsolateral third ventricle, and in the pineal anlage (epiphysis). ChAT IR neurons continued to develop in these and additional germinal zones on GD15, including the medial, dorsal, and dorsomedial walls of the lateral ventricle, and the medial and dorsal ganglionic eminence. On GD16, ChAT IR neurons were located in the prelimbic, pyriform, and parietal cortices and the lamina terminalis, and a cluster of IR cells was observed in the ventricular zone of the caudatopallial angle. On GD17–18, neurons in the anterior olfactory nucleus, olfactory tubercle, horizontal and vertical nucleus of the diagonal band, and medial septal nucleus stained more darkly and were multipolar, whereas immature bipolar neurons appeared to continue their migration into the hippocampus and along major fiber tracts, such as the corpus callosum, external capsule, fornix and anterior commissure.This study provides a comprehensive view of the zones of origin, probable routes of migration, and final destination of cholinergic neurons in the mouse fo

ISSN:0092-7317    

DOI:10.1002/cne.902880109

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

年代:1989

数据来源: WILEY

摘要:

AbstractIn the urodele speciesSalamandra salamandraandBatrachoseps attenuatus, the distribution of the neuropeptides substance P (SP), leucine‐enkephalin (LENK), and bombesine (BOMB) was investigated by means of immunohistochemistry in brain areas containing retinofugal projection sites (tectum mesencephali, praetectum, thalamus) as well as in brain regions postsynaptic to the tectum. The activity of acetylcholinesterase (AChE) was studied histochemically.Despite its simplified, two‐layered morphology, the salamander tectum shows a high degree of neurochemical differentiation, characterized by a laminar organization of neuropeptide‐like immunoreactivity and AChE‐activity comparable to that found in the anuran tectum, which has a multi‐layered morphology. SP‐like immunoreactivity constituted four tectal laminae, two of them occurring in the stratum opticum. LENK‐like immunoreactivity formed three laminae, one in the stratum opticum. BOMB‐like immunoreactivity formed one lamina within the stratum opticum and one in the tectal efferent layers. Layers 1 and 2 of the stratum opticum revealed high AChE‐activity, whereas low activity was found in deep fiber layers containing tectal efferents. The outer cellular layer also revealed AChE‐activity. After enucleation of one eye, the contralateral tectum lacked neuropeptide‐like immunoreactivity and AChE‐activity in the layers containing retinofugal projection sites. No reduction of immunoreactivity was found in nuclei postsynaptic to the tectum.Our experiments suggest that the secondary simplification that has taken place in salamanders with respect to tectal morphology did not affect the neurochemical differ

ISSN:0092-7317    

DOI:10.1002/cne.902880110

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

年代:1989

数据来源: WILEY

摘要:

AbstractFMRFamide‐like immunoreactivity (FLI) and the colocalization of FMRFamide and subtance P‐like (SPLI) immunoreactivities were examined in the brain and lateral eye of the horseshoe crab with FITC‐ and TRITC‐ labeled secondary antibody techniques. In the brain, fibers with FLI were localized in the neuropils of the lamina, medulla, central body, corpus pedunculatum, optic tract, circumesophageal connective, and central neuropil. An extensive network of reactive fibers innervates the brain's vascular sheath. Somata with FLI were found in the dorsal medial group, dorsal lateral posterior groups #1 and #2, and ventral posterior lateral groups #1 and #2. Several distinct subgroups of reactive somata were noted in both the medullar and ventral medial groups.The distribution of fibers in the brain with colocalized FLI and SPLI includes those which innervate the vascular sheath and widespread populations of small‐diameter beaded fibers in the central neuropil and circumesophageal connective. Somata with colocalized FLI and SPLI constitute minority populations in the medullar and dorsal medial groups but form the majority population of a subgroup in the ventral medial group.Overall localization of SPLI was reevaluated and is reported here according to the nomenclature of the new Chamberlain and Wyse brain atlas. In addition to those previously reported, somata with SPLI were found in the dorsal lateral posterior groups #1 and #2, the ventral lateral posterior groups #1 and #2, and several distinct subgroups of the medial and ventral medial groups.In the retina of the lateral eye, fibers with both FLI and SPLI ramify in the lateral plexus and ultimately innervate the corneal epidermis.Brain homogenates were examined for immunoreactive (ir) FMRFamide and ir–substance P with radioimmunoassay techniques. Ir‐FMRFamide and ir–substance P eluted in different fractions from both gel filtration chromatography and HPLC. Furthermore, the binding curves for both substances were similar to those of the corresponding synthetic compounds.Brain homogenates were also bioassayed on the lateral eye. Three gel filtration fractions mimic natural circadian activity by increasing the sensitivity of the lateral eye, but they were not coincident with ir‐FMRFamide or ir–substance P. Although it is not completely resolved what the active molecules in these fractions are, it is clear that neither ir‐FMRFamide nor ir–substance P

ISSN:0092-7317    

DOI:10.1002/cne.902880111

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

年代:1989

数据来源: WILEY