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V Lemmon

Publications and source records attributed to V Lemmon.

63 records · Page 4Linked to original sources
PubMed1985

Monoclonal antibodies specific for glia in the chick nervous system.

Two monoclonal antibodies that bind to previously undescribed glial antigens are discussed. One antibody, 3A7, binds to Müller cells in the chick retina and radial glia in the optic tectum. The other, 7G4, also binds to Müller cells, However, in the tectum it binds to a small cell type in the stratum opticum. The developmental appearance of the antigens and their localization in cells in tissue culture are also presented.

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PubMed1983

The development distribution of vimentin in the chick retina.

The developmental distribution of vimentin was localized in chick retina using light and electromicroscopic immunohistochemical techniques. From embryonic day 4 (E4) to E8 vimentin was present in cells throughout the retina. By E10 vimentin immunoreactivity was restricted to Müller cells. In tissue culture of chick neural retina vimentin was found to be restricted to flat cells that are thought by others to be derived from Müller cells. Neurons in culture did not contain vimentin.

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PubMed1982

Afferent and efferent connections of the striate and extrastriate visual cortex of the normal and reeler mouse.

In order to analyze the role of lamination in establishing the precisely ordered connectional pattern of the neocortex, we compared the afferent and efferent connections of the visual cortical areas in normal mice with those of the mutant mouse reeler (rl). The reeler mutation causes disruption of the laminar organization of the neocortex; all classes of neurons are present but are abnormally located. The corticocortical and thalamocortical connection os visual cortical areas 17, 18a, and 18b were determined in normal and reeler mice with injections of horseradish peroxidase (HRP) or HRP conjugated with wheat germ agglutinin (HRP-WGA). The diffusion of HRP-WGA is highly restricted due to the surface binding properties of the lectin; it was particularly effective in demonstrating retinotopically ordered connections. We found that the patterns of connections made the reeler mutant are indistinguishable from normal. Cortical loci in area 17 are reciprocally connected to homotopic locations in areas 18a and 18b. Area 17 is also reciprocally connected with dorsal lateral geniculate nucleus of the thalamus and projects to the superior colliculus. Areas 18a and 18b are reciprocally connected with each other and with the lateral posterior and lateral nuclei of the thalamus, respectively. In addition, we found evidence of reciprocal connections between the lateral posterior nucleus and area 17, and between the lateral nucleus and areas 17 and 18a. The results indicate the neurons in visual cortical areas of the reeler mutant mouse are capable of forming retinotopically organized corticocortical and thalamocortical connections in a pattern similar to that found in normal animals. Thus the genetic anomaly producing incorrect neuronal positioning during development of the reeler cortex does not seriously impede the pathway and target recognition mechanisms responsible for formation of functionally appropriate cortical connections.

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PubMed1982

A monoclonal antibody which binds to the surface of chick brain cells and myotubes: cell selectivity and properties of the antigen.

A monoclonal antibody has been obtained which binds to the cell surface of cultured chick myotubes and retinal and tectal neurons but not fibroblasts, myoblasts and embryonic liver cells. Indirect immunocytochemistry reveals that antigen is present in all layers of the chick neural retina. The antibody therefore recognizes an antigen common to most, if not all, chick neurons. The antigen has been identified by staining SDS gels with [125I]monoclonal antibody and appears to be a polydisperse collection of polypeptides with molecular weights centered about 250 kdalton.

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PubMed1982

Monoclonal antibodies selective for the inner portion of the chick retina.

Five monoclonal antibodies were selected by immunizing mice with embryonic chick optic nerve and screening the resultant hybridoma antibodies by immunofluorescence on sections of the retina. The optic nerve was chosen as the immunizing tissue since it is presumably enriched in ganglion cell-specific antigens. These antibodies bind to antigens which are largely localized to the inner part of the retina. Two of the antibodies, RET1 and RET2, show highly selective binding to the optic fiber layer. Another, RET3, stains the optic fiber layer, ganglion cell layer, and inner plexiform layer. Antibody RET4 stains the optic fiber layer, ganglion cell layer, inner plexiform layer, and the inner one-half of the inner nuclear layer; this antibody binds to an antigen on or associated with the plasma membrane. Antibody RET5 stains the retinal ganglion cell layer faintly and the inner and outer plexiform layers strongly. The potential utility of these antibodies for future studies on retinal development is discussed.

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PubMed1981

Does laminar position determine the receptive field properties of cortical neurons? A study of corticotectal cells in area 17 of the normal mouse and the reeler mutant.

The neocortex of the reeler (rl) mutant mouse develops abnormally; as a result, the orderly arrangement of cells in laminae containing neurons of similar size and configuration is severely disrupted. The reeler mutant thus offers an opportunity to study the role played by laminar position in establishing the interneuronal connections of the cortex. Since the receptive field properties of neurons in the primary visual cortex (area 17) are determined by these complex interconnections, a study of receptive field properties provides a useful way to test whether functionally important connections are altered by abnormal cell position. We chose the corticotectal (CT) cells of area 17 for this analysis because they have distinctive receptive field properties and can be identified positively by antidromic stimulation with electrodes in the superior colliculus. In addition, CT cells are located in a single lamina (layer V) in the visual cortex of normal mice, but are distributed from surface to white matter in the reeler visual cortex. We characterized the receptive fields of identified CT cells in area 17 of normal mice and reeler mutants and studied several properties of these cells quantitatively. Corticotectal cells in the visual cortex of the normal mouse have high rates of spontaneous activity and large receptive fields that are neither oriented nor directional; they respond to moving stimuli over a wide range of stimulus velocities, have high peak velocity sensitivities, and show very little spatial summation. Corticotectal cells in the visual cortex of the reeler mutant do not differ significantly in these characteristics, although CT cells with extremely large receptive fields are encountered somewhat more frequently in reeler cortex. These findings indicate that the detailed connections which determine the receptive field properties of CT cells are properly established in the reeler mutant mouse despite the markedly abnormal positions of CT cells in reeler visual cortex.

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PubMed1977

Response properties of cells in the dorsal lateral geniculate nucleus of the albino rat.

The response patterns of cells in the dorsal lateral geniculate nucleus of the albino rat were studied in order to examine the functional organization of the lateral geniculate nucleus. Both photic stimulation and electrical stimulation of the optic tract were used to activate single units in the lateral geniculate nuclei. Three different types of response patterns were found for principal cells, while interneurons all had similar response patterns. The first class of principal cells, E-S cells, responded to stimulation with a period of excitation, followed by a period when activity was suppressed. A second class of cells, S cells, responded to photic stimulation with an initial period when activity was suppressed. The final class of cells, E cells, responded with a period of excitation followed by a return to spontaneous rates of firing. The response patterns of E cells suggest that this type of principal neuron does not receive feedback inhibition of the type proposed in previous models of the lateral geniculate nuclei. Based on these and other observations, a new model of the functional organization of the lateral geniculate nuclei is proposed.

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