Photoreceptors amacrine cells

Keywords Amacrine cell Bipolar cell Cone Fovea Horizontal cell Muller cells Photoreceptor Retina Retinal ganglion cell Rod... 

Figure 11.2. The five major retinal cell types (photoreceptors, bipolai cells, horizontal cells, amacrine cells, and ganglion cells) and tlieir synaptic connections.

A fully developed retina consists of six neuron types and the Muller glial cells as shown in this schematic representation. A, Amacrine cells B, bipolar cells C, cone photoreceptor cells G, ganglion cells H, horizontal cells I, interplexiform cells M, Muller cells PE, pigment epithelium R, rod photoreceptor cell INL, inner nuclear layer IPL, inner plexiform layer ONL, outer nuclear layer Ph, photoreceptors RPE, RPE (Reproduced with permission from the publishers of Sharma and Ehinger, 2003)... 

In the rat retina, mGluR5 immunoreactivity in the outer and inner plexiform layers was further observed electron-microscopically immunoreactivity in the outer plexiform layer was in dendrites of rod bipolar cells postsynaptic to rod photoreceptor terminals, while that in the inner plexiform layer was seen in amacrine cell processes postsynaptic to OFF-cone bipolar cell terminals, ON-cone bipolar cell terminals, and rod bipolar cell terminals (Koulen et al., 1997). 

ENT (OCT 3) Epi NE >DA Liver Brain Heart Blood vessels Kidney Placenta Retina Hepatocytes Glial cells, others Myocytes Endothelial cells Cortex, proximal and distal tubules S y ncytiotrophoblast (basal membrane) Photoreceptors, ganglion amacrine cells Isocyanines, corticosterone, 0-methyl- isoproterenol... 

Figure 2. Micrographs of TH-immunoreactive cells in a retina of an untreated control animal (A) and in a retina of a monkey exposed to 600 ppm lead over nine years with a subsequent 32-month period of lead-free diet (B). Note the decrease in fluorescence intensity in the cell bodies (arrows) and in the fibre layer (arrowheads). An unlabeled amacrine cell (asterisk) is surrounded by stained fibre. The outer segments of the photoreceptors (PhR) show an unspecific fluorescence. INL inner nuclear layer, IPL inner plexiform layer, calibration bar 30 pm...

The retina extends forward to the sclera as a globe-shaped wineglass almost external to the skull. That part of the sclera devoid of retina is the pars planar, which is used as an access point for injection or for close delivery to the iris and ciliary body (ICB). When stripped from its basement membrane and opened out, the collapsed retina is a circular disk approximately 42 mm in diameter and 0.5 mm in thickness. The organization of the retina is based on a three-neuron chain (photoreceptor cell-bipolar cell-ganglion cell) and accompanying cells (horizontal, amacrine, and Muller cells)... 

Kljavin IJ, Lagenaur C, Bixby JL, Reh TA. 1994. Cell adhesion molecules regulating neurite growth from amacrine and rod photoreceptor cells [published erratum appears in J Neurosci 1994 Oct 14(10) Following table of contents]. J Neurosci 14 5035-5049. 

Politi LE, Insua E, Buzzi E. 1998. Selective outgrowth and differential tropism of amacrine and photoreceptor axons to cell targets during early development in vitro. J Neurosci Res 52 105-117. 

The smaller amount of neurons driven by the more numerous cones points to a complex wiring of these receptors located in the second layer of the retina. The inner nuclear layer connects the photoreceptors with the ganglion cells and consists of bipolar, amacrinal, and horizontal cells. Bipolar cells can be divided into ON and OFF bipolars. The OFF bipolar cells inhibit the release of neurotransmitters after a photon triggered increase in electrical potential whereas the ON bipolar cells stimulate the release of neurotransmitters. This allows the visual system to build differential signals already in the first processing stage (see Fig. 5). 

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