The morphology of horizontal cells chiefly of the horse, but also of asses, mules, and a zebra, has been examined by Lucifer yellow injections into lightly fixed retinae and by immunocytochemistry. In common with other mammals, equids have a B-type horizontal cell, i.e., a cell with dendrites synapsing with cones and possessing a single axon synapsing with rods. Most mammalian retinae have a further type of horizontal cell, the A-type, also synapsing with cones but without an axon. The second type of horizontal cell in equids also has no axon; otherwise, it is most unusual. Compared with other mammalian A-type cells, it has a vary large dendritic field, both absolutely and relative to the dendritic fields of B-type cells. The dendrites are fine and sparsely branching. Their most striking feature is that they bear a low density of irregularly spaced synaptic terminal aggregates, suggesting their cone contacts are selective. Immunolabelling of S (blue)-cones in horse retina showed that they comprise, depending on retinal location, 10-25% of the cone population. For a single horse A-type cell, it is shown that 44 of its 45 terminal aggregates are congruent with the pedicles of S-cones. Immunostaining with a calbindin antibody demonstrated that each type of horizontal cell forms an independent regular mosaic. The density ratio of B- to A-type cells varied between 5 and 10. This is the first demonstration in a mammalian retina of a horizontal cell type with a direct input exclusively from S-cones.
BACKGROUND AND PURPOSE:In PD, tissue damage occurs in specific cortical and subcortical regions. Conventional MR images have only limited capacity to depict these structural changes. The purpose of the current study was to investigate whether voxel-based MT imaging could indicate structural abnormalities beyond atrophy measurable with T1-weighted MR imaging.
In all mammalian retinae studied to date, starburst cholinergic amacrine cells are a consistently occurring cell type. Here, we show that the cone-dominated retina of the tree shrew also has starburst cells with the characteristic radially symmetric branching pattern known from other species. Dendritic field sizes increase from 150 microm in the central retina to 300 microm in the retinal periphery. The characteristic morphology is established early during postnatal development. Labelling the starburst cholinergic cells with an antibody against choline acetyltransferase (ChAT) reveals two dendritic strata in the inner plexiform layer and two corresponding soma populations in the inner nuclear layer (orthotopic) and ganglion cell layer (displaced). These features are present in the adult and in early postnatal stages. In the adult, the density of the orthotopic population as well as the displaced population peaks in the central retina at about 2,200 cells/mm2 and has a peripheral minimum of 400 cells/mm2. These properties are qualitatively similar to those of starburst cells in rod-dominated retinae. In contrast to findings in other mammals, we did not see gamma-aminobutyric acid (GABA) or glutamic acid decarboxylase 65 kDa (GAD65) immunoreactivity in tree shrew starburst cells. These cells also appear to lack synaptophysin, a ubiquitous synaptic vesicle protein detected in the starburst cells of some other mammals. However, synaptoporin, a homologous synaptic vesicle protein, appears to be present in tree shrew starburst cells.
In all mammalian retinae studied to date, starburst cholinergic amacrine cells are a consistently occurring cell type. Here, we show that the cone-dominated retina of the tree shrew also has starburst cells with the characteristic radially symmetric branching pattern known from other species. Dendritic field sizes increase from 150 microm in the central retina to 300 microm in the retinal periphery. The characteristic morphology is established early during postnatal development. Labelling the starburst cholinergic cells with an antibody against choline acetyltransferase (ChAT) reveals two dendritic strata in the inner plexiform layer and two corresponding soma populations in the inner nuclear layer (orthotopic) and ganglion cell layer (displaced). These features are present in the adult and in early postnatal stages. In the adult, the density of the orthotopic population as well as the displaced population peaks in the central retina at about 2,200 cells/mm2 and has a peripheral minimum of 400 cells/mm2. These properties are qualitatively similar to those of starburst cells in rod-dominated retinae. In contrast to findings in other mammals, we did not see gamma-aminobutyric acid (GABA) or glutamic acid decarboxylase 65 kDa (GAD65) immunoreactivity in tree shrew starburst cells. These cells also appear to lack synaptophysin, a ubiquitous synaptic vesicle protein detected in the starburst cells of some other mammals. However, synaptoporin, a homologous synaptic vesicle protein, appears to be present in tree shrew starburst cells.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.