![]() Mouse is a favored model because of the ability of transgenic resources. Great insights into these mechanisms have been revealed recently through the use of model organisms, particularly mouse, chick, and zebrafish. Our understanding of the process and molecular mechanisms that result in the generation, differentiation, patterning, and subsequent wiring of numerous neuronal types continues to grow, yet remains incomplete. The mature vertebrate retina, with its stereotypical laminar and mosaic organizations, is derived from an apparently uniform, single-layered retinal neuroepithelium during development. Figure from ( Harada et al., 2007), with permission. Forebrain neuroectoderm (blue) contributes to RPE, iris, and neural retina surface ectoderm contributes to lens and cornea (green) neural crest contributes to cornea, choroid, and sclera (pink), and mesoderm contributes to extraocular muscles and cornea (yellow). This regularity of two-dimensional neuronal pattern is likely functionally important for representative sampling of the visual field.įormation of the major tissues of the eye. In teleost fish the cone photoreceptor mosaics may be geometrically precise Fig. ![]() Each of the six major retinal neuronal categories (rod, cone, horizontal cell, bipolar cell, amacrine cell, RGC) includes numerous specific morphological and functional subtypes, and many of these subtypes are distributed across the retinal sheet in regularly spaced mosaics. In addition to cells generated from retinal progenitor cells, the retina also contains astrocytes, microglia, and cells of the retinal vasculature. MGs are known to respond to retinal injury or disease by re-entering the cell cycle, and in some nonmammalian vertebrates can generate new neurons that functionally integrate into the retina ( Bernardos, Barthel, Meyers, & Raymond, 2007 Fausett & Goldman, 2006 Sherpa et al., 2008 Sherpa et al., 2014). MGs have cell bodies which reside in the INL, and processes that span the retina, providing structure to the retina as well as supporting homeostasis. ![]() The final major cell type derived from retinal progenitors is the Müller glial cell (MG). Bipolar cells, horizontal cells, and amacrine cells, which have cell bodies located in the inner nuclear layer (INL) between the photoreceptors and ganglion cells, process and transmit information from photoreceptors to the ganglion cells, allowing for the extraction of features from the visual field including luminance contrast, color contrast, and movement. The innermost layer of the retina (retinal ganglion cell layer GCL) contains cell bodies of retinal ganglion cells (RGCs), which are the output neurons of the retina, projecting axons via the optic nerve and tract to specific targets in the brain. Rods and cones detect photons and convey this information by chemical signaling. The outermost layer (outer nuclear layer ONL) contains the cell bodies of photoreceptors (rods and cones), which project their inner and outer segments toward the adjacent retinal pigmented epithelium (RPE). The vertebrate retina contains seven major cell types organized into three layers of cell bodies termed nuclear layers, separated by two synaptic, or plexiform layers ( Fig.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |