摘要:

AbstractThe cellular morphology and topographic distribution of the rod bipolar cells in the rabbit retina have been investigated by selective labelling with protein kinase C‐immunohistochemistry (Negishi et al., Neurosci. Lett.94:247–252, 1988) and by Lucifer Yellow injection of microscopically identified cells in a superfused retinal preparation. The distribution of the rod bipolar cells parallels that of their input neurons, the rod photoreceptors, in that the rod bipolars reach maximum densities of 5,000–7,000 cells/mm2on the inferior and superior flanks of the visual streak, dropping to slightly lower densities at the peak visual streak. The centre‐to‐periphery density gradient of the rod bipolars is about 2.5:1, and the density ratio of rods to rod bipolars shows little variation across the retina, ranging from 43:1 in superior retina to 58:1 in inferior retina. The dendritic field area of the rod bipolar cells increases from 600 μm2on the visual streak to 1,200 μm2in the far‐superior retina, with each point on the retina overlapped by 2.5–3.5 dendritic fields. The axonal field area of the rod bipolar cells increases from about 100 μm2at the peak visual streak to about 250 μm2at the retina edge, and the axonal field coverage ranges from 0.55 in the visual streak to about 0.8 in peripheral retina. Although there appear to be gaps in the local array of rod bipolar somata, these areas are covered by the axonal arbours of neighbouring

ISSN:0092-7317    

DOI:10.1002/cne.903100202

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

年代:1991

数据来源: WILEY

摘要:

AbstractAII amacrine cells, which are the third‐order neurons in the rod pathway, can be differentially labelled in rabbit retina by injecting Nuclear Yellow into the posterior chamber. Under ultraviolet excitation, the labelled retina appears strongly metachromatic, with the AII nuclei fluorescing silvery‐yellow and the nuclei of other amacrine cells fluorescing blue. Labelled AH cells were injected with Lucifer Yellow under direct microscopic control in a superfused retinal preparation, and the dye was later photoconverted to an opaque reaction produc.Rabbit AII amacrines, which number about 525,000 cells, reach a maximum density of 2,500–3,000 cells/mm2on the peak visual streak, dropping to 400–500 cells/mm2at the superior margin. These narrow‐field amacrines have a bistratified dendritic morphology, with distinctive “lobular appendages” in sublaminaaof the inner plexiform layer and wider ranging “arboreal dendrites” in sublaminab. Although the lobular field area increases 10‐fold from the visual streak to the far periphery, the lobular field coverage is almost uniform across the retina, averaging 1.0 in inferior retina and 0.8 in superior retina. The dendritic field area of the arboreal dendrites also increases with eccentricity from the visual streak, but there are pronounced differences between inferior and superior retina. The arboreal fields are 2 to 3 times larger than the lobular fields throughout the inferior retina but up to 15 times larger in the superior retina. The arboreal field overlap is only 1.8 at the peak visual streak, increasing slightly to about 2.4 over most of the inferior retina; the overlap increases sharply in the superior retina, however, reaching values of 10 or more in the far periphery. Both the lobular and arboreal fields of AII cells are spaced more regularly than the somata, thus covering apparent gaps in the somatic arra.An analysis of the potential convergence and divergence between rod bipolar cells and AII amacrine cells in the rabbit retina indicates that the neuronal architecture of the rod circuit is not organized in a uniform module that is simply scaled‐up from central to peripheral retina. Moreover, peripheral fields in the superior and inferior retina that have equivalent densities of interneurons show markedly different rod bipolar → AII amacrine convergence ratios, with the result that many more rod photoreceptors converge on an AII amacrine cell in the superior retina than in the inferior retina. In the rabbit retina, much of the convergence in the rod circuit must occur in the outer retina, whereas, in the central cat retina, it is more evenly distributed between th

ISSN:0092-7317    

DOI:10.1002/cne.903100203

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe localization of phosphatase inhibitor‐1 was investigated in rat brain by use of immunocytochemistry. Studies were performed with an affinity purified IgG raised against purified rabbit skeletal muscle inhibitor‐1. In rat brain tissue homogenates, this antibody reacted only with a 29 kDa protein corresponding to inhibitor‐1. Immunocytochemical studies with this antibody revealed numerous immunoreactive cell bodies and fibers. The highest concentration of immunoreactive perikarya was observed in the caudate‐putamen and nucleus accumbens, and these appeared to be exclusively medium‐sized neurons. Other areas containing substantial populations of immunoreactive neurons included the suprachiasmatic nucleus of the hypothalamus, lateral hypothalamus, horizontal limb of the diagonal band of Broca, dentate gyrus of the hippocampal formation, habenula, superior colliculus, claustrum, endopiriform nuclei, and neocortex. The distribution of terminals containing inhibitor‐1 coincided with the distribution of terminal fields known to originate from the above regions. Thus, plexuses of immunoreactive axons were seen in the globus pallidus, substantia nigra pars reticulata, para ventricular hypothalamus, dorsal thalamus, CA3 region of the hippocampus, and interpeduncular nucleus. These results demonstrate that phosphatase inhibitor‐1, a cyclic AMP‐regulated inhibitor of phosphatase‐1, is differentially distributed in the rat CNS. Given the widespread role of protein phosphorylation and dephosphorylation in intracellular signal transduction, these results suggest that neurons containing high levels of inhibitor‐1 may share common, hitherto unrecognized, properties in terms of neurotransmitter regulation a

ISSN:0092-7317    

DOI:10.1002/cne.903100204

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

年代:1991

数据来源: WILEY

摘要:

AbstractSomatostatin (SRIF, S14) receptors in the cat and monkey visual cortex were visualized by means of in vitro autoradiography with an iodinated agonist of SRIF, [125I‐Tyr0, DTrp8]S14. The kinetics, performed on tissue sections, revealed an apparently single, saturable site (KD= 3.92 ± 0.31 10−10M for the cat, and 3.82 ± 0.28 10−10M for the monkey visual cortex) with pharmacological specificity for S14 and [DTrp]‐substituted S14. Autoradiography, performed on frontal sections of the cat and monkey visual cortex, revealed a heterogeneous regional and laminar distribution of SRIF receptor.In cat areas 17, 18, and 19, SRIF receptors occur mainly in the supragranular layers, although small interareal and intra‐areal differences are observed. The infragranular layers (V–VI) in area 19 contain a significantly higher proportion of SRIF receptors compared to both areas 17 and 18. In the antero‐ (AMLS) and posteromedial lateral suprasylvian area (PMLS), layers V and VI contain the highest proportion of SRIF receptors. This latter pattern is also observed in the area prostriata medially adjoining area 17 in the splenial sulcu.In the monkey visual cortex, areas 17 and 18 exhibit similar distribution patterns, SRIF receptors being primarily concentrated in layers V and V.Neither in the cat nor the monkey visual cortex could we observe significant differences in SRIF receptor distribution between different retinotopic subdivisions

ISSN:0092-7317    

DOI:10.1002/cne.903100205

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

年代:1991

数据来源: WILEY

摘要:

AbstractWe have studied the postnatal development of individual axons in the optic tract and thalamus of the Syrian hamster, concentrating attention on retinal ganglion cell axons that make a transient projection to the main somatosensory nucleus, the ventrobasal complex. We bulk‐filled axons with horseradish peroxidase in hemithalami maintained en bloc, in vitro. After processing and reaction with diaminobenzidine, we reconstructed individual axons from serial sections. In hamsters and other rodents, the optic tract is composed of superficial and internal components, either or both being possible sources of the retino‐ventrobasal projection. Both project to the midbrain, but in normal adults only the superficial optic tract maintains collaterals in the thalamus. We found that the axons of the internal component bear numerous transient thalamic collaterals on postnatal days 0, 1, and 2, and some of these extend into the ventrobasal complex. Axons in the superficial optic tract also bear collaterals on days 0 to 2, but these are confined to the superficial half of the dorsal lateral geniculate nucleus. Thus the transient retino‐ventrobasal projection comprises solely transient collaterals originating from axon trunks in the internal optic tract. On days 1 and 2, some collaterals from the superficial optic tract appear to have begun to arborize in the lateral geniculate nucleus. In contrast, collaterals from internal optic tract axons to the ventrobasal complex branch little if at all as they traverse the lateral geniculate nucleus, and at no time prior to their elimination do they develop an appreciable terminal arbor. These long collaterals often terminate in growth cones that include lamellopodia. Our HRP‐impregnation method also revealed some transient non‐retinofugal axons that pass medially from the ventral lateral geniculate nucleus to the ventrobasal complex but then return without terminating or branching. By day 4, they are absent, as are collaterals from the internal optic tract to the ventrobas

ISSN:0092-7317    

DOI:10.1002/cne.903100206

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

年代:1991

数据来源: WILEY

摘要:

AbstractMonoclonal antibody (mab) anti‐zebrin II recognizes a single 36‐kD polypeptide in Purkinje cells in the rat and fish cerebellum. In the adult rat, zebrin II+Purkinje cells form, in each hemicerebellum, seven parasagittal bands interposed by zebrin II−bands. We show that, in rats, immunoreactivity first appears caudally at postnatal day 5 and spreads; all Purkinje cells are labelled by postnatal day 12. Subsequently, immunoreactivity is selectively lost so that by day 18 the adult pattern of zebrin II+/−immunoreactive bands is created. This pattern indicates two types of Purkinje cells according to developmental trajectory, zebrin II−/+and zebrin II−/+/−.In the adult gymnotiform teleostEigenmannia, Purkinje cells in the corpus cerebelli (CCb), lateral valvula cerebelli (VCbl), and eminentia granularis anterior (EGa) are zebrin II+Purkinje cells in the eminentia granularis posterior (EGp) and medialis (EGm) and the medial valvula cerebelli (VCbm) are zebrin II−. Zebrin II antigenicity is first present at 6 days postspawning (P6) in the EGa and at P8 in the CCb. In the valvula, labelling does not appear until P29. Immunoreactivity in the CCb, VCbl, and the EGa persists in the adult, whereas in the VCbm Purkinje cells become zebrin II−before reaching adulthood. These developmental histories (zebrin II−/+and zebrin II−/+/−) correspond to the patterns of Purkinje cell development in mammals. Additionally,Eigenmanniahas a third class of Purkinje cells, in the EGp and EGm, that never express zebrin II immunoreactivity, indicating that zebrin II expression is not an obligatory feature of Purkinje cell develo

ISSN:0092-7317    

DOI:10.1002/cne.903100207

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe earliest developing interneurons in the chick spinal cord can be divided into two groups: neurons in the ventral region whose axons pioneer the primitive longitudinal pathway (PL‐cells) and neurons whose axons project circumferentially (C‐cells) along the lateral marginal zone and join the ipsilateral or contralateral ventrolateral longitudinal pathways. To begin to examine the molecular cues for axonal pathway formation of these interneurons, we screened a variety of molecules from embryonic day (E) 2 to E6.5 [stage 14–30 of Hamburger and Hamilton (1951) J. Morphol.88:49–92]. These include cell adhesion and related molecules (G4, F11, neurofascin, N‐cadherin, TAG‐1‐like molecule), extracellular matrix (ECM) molecules (laminin, fibronectin, heparan sulfate proteoglycan, laminin‐heparan sulfate proteoglycan complex, and collagen type IV), and receptors for ECM molecules (β1‐class integrin). PL‐cells first expressed neurofascin at stage 14+ before the onset of axonogenesis. When the PL‐cells began to extend their axons at stage 15, they expressed G4 and avian TAG‐1‐like molecules, as well as neurofascin, on both cell bodies and longitudinal axons. In the following stages, PL‐cells continued to strongly express neurofascin and G4 on their fasciculating axons, suggesting the involvement of these glycoproteins in growth and fasciculation. C‐cells began to express G4 and TAG‐1‐like molecules on cell bodies and axons at stage 15–16 shortly after axonal growth. In the following stages, C‐cells expressed several cell adhesion molecules differentially on their axonal segments. The proximal segment of C‐axons in the circumferential pathway strongly expressed a TAG‐1‐like molecule, whereas the distal segment in the longitudinal pathway strongly expressed G4 and neurofascin. The commissural axonal segment in the floor plate expressed TAG‐1‐like molecule, neurofascin, N‐cadherin, and β‐class integrin. The basement membrane around the spinal cord was enriched with ECM glycoproteins (laminin, fibronectin, heparan sulfate proteoglycan, and collagen type TV) during the stages examined (stage 15–27), and commissural C‐cell axons became strongly integrin positive in the floor plate where they contacted the basement membrane. These data indicate that interneurons may use multiple molecules during axonal pathway formation, dependi

ISSN:0092-7317    

DOI:10.1002/cne.903100208

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe synaptic organization of the projection from the cat striate visual cortex to the posteromedial lateral suprasylvian cortical area (PMLS) was examined. The anterograde tracerPhaseolus vulgarisleucoagglutinin (PHA‐L) was iontophoretically delivered into area 17, and anterogradely labeled fibers were revealed in PMLS by means of an immunocytochemical detection method. Most axons and presumptive terminal swellings were found in layers III and IV. The neuronal elements (n = 190) that were postsynaptic to anterogradely labeled boutons were quantitatively analyzed. All anterogradely labeled cortico‐cortical boutons (n = 182) established type 1 synapses. The results show that 83% of the postsynaptic targets were dendritic spines, probably belonging to pyramidal cells. Dendritic shafts constituted 17% of the targets. The dendritic shafts postsynaptic to cortico‐cortical boutons were studied for the presence of gamma‐aminobutyric acid (GABA) with a postembedding immunogold method. Most dendritic shafts (85%) that were tested were found to be GABA‐positive, demonstrating that they originate from local inhibitory neurons. Taking into account that most postsynaptic targets were spines and extending the results of the immunocytochemical testing to the total population of postsynaptic dendrites, it was calculated that at least 14% of targets originated from GABA‐positive cell.Thus cortico‐cortical axons establish direct monosynaptic connections mainly with pyramidal and to a lesser extent with GABAergic nonpyramidal neurons in area PMLS, providing both feedforward excitation and feedforward inhibition to a visual associational area known to be involved in the processing of motion information. The results are consistent with previously demonstrated deficits in physiological properties of neurons in PMLS following removal of cortico‐co

ISSN:0092-7317    

DOI:10.1002/cne.903100209

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

年代:1991

数据来源: WILEY

摘要:

AbstractPostembedding electron microscope immunocytochemistry of glycine and GABA conjugated to colloidal gold has been applied to pre‐embedded cat retina stained with the antibody against tyrosine hydroxylase (Toh+). Toh+ stained cells are the equivalent of A18 amacrine cells of Golgi descriptions (Kolb et al., 1981). The dendrites of Toh+ cells synapse upon several different types of glycine‐positive amacrine cell bodies. We suggest that these are the A8, A3/A4, and AII amacrine cell varieties by analogous immunocytochemical staining intensity, to glycine autoradiographic labeling intensity (Pourcho and Goebel, 1985). The greatest number of synapses from Toh+ dendrites are directed at the least glycine‐positive amacrine, which is the AII cell by all morphological criteria. A few glycine‐positive profiles are also presynaptic to the Toh+ stained cell body itself.Toh+ profiles are also presynaptic to GABA‐positive amacrine cell bodies. The commonest amacrine synapsed upon is very heavily labeled with GABA immunocytochemistry. We consider it to be the A17 amacrine cell, which is known to label strongly by [3H] muscimol autoradiography (Pourcho and Goebel, 1983). The cell body of the Toh+ amacrine cell also receives many synapses, which appear to be GABA‐positive, and Toh+ profiles running in stratum 1 of the inner plexiform layer (IPL) are both pre‐ and postsynaptic to GABA‐positive amacrine cell profiles. In addition, the cell body and primary dendrites of the Toh+ cell receive input from a bipolar type and GABA‐ or glycine‐negative profiles. GABA‐positive profiles, belonging to the interplexiform cell (IPC), are synapsed upon by Toh+ profiles that run in the outer plexiform layer (OPL). Horizontal cells identified on morphological criteria as the B‐type may also rece

ISSN:0092-7317    

DOI:10.1002/cne.903100210

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

年代:1991

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.903100201

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

年代:1991

数据来源: WILEY