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| Retinal pigment epithelium | |
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| Section of retina. (Pigmented layer labeled at bottom right.) | |
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| Plan of retinal neurons. (Pigmented layer labeled at bottom right.) | |
| Latin | p. pigmentosa retinae |
| Gray\'s | subject #225 1016 |
| Dorlands/Elsevier | p_07/12617535 |
The retinal pigment epithelium (RPE) is the pigmented cell layer just outside the neurosensory retina that nourishes retinal visual cells, and is firmly attached to the underlying choroid and overlying retinal visual cells.Cassin, B. and Solomon, S. (2001). Dictionary of eye terminology. Gainesville, Fla: Triad Pub. Co. ISBN 0-937404-63-2. Boyer MM, Poulsen GL, Nork TM. "Relative contributions of the neurosensory retina and retinal pigment epithelium to macular hypofluorescence." Arch Ophthalmol. 2000 Jan;118(1):27-31. PMID 10636410.
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The RPE is composed of a single layer of hexagonal cells that are densely packed with pigment granules.
When viewed from the outer surface, these cells are smooth and hexagonal in shape. When seen in section, each cell consists of an outer non-pigmented part containing a large oval nucleus and an inner pigmented portion which extends as a series of straight thread-like processes between the rods, this being especially the case when the eye is exposed to light.
The retinal pigment epithelium is involved in the phagocytosis of the outer segment of photoreceptor cells and it is also involved in the vitamin A cycle where it isomerizes all trans retinol to 11-cis retinal.
The retinal pigment epithelium also serves as the limiting transport factor that maintains the retinal environment by supplying small molecules such as amina acid, ascorbic acid and D-glucose while remaining a tight barrier to choroidal blood borne substances. Homeostasis of the ionic environment is maintained by a delicate transport exchange system.
In the eyes of albinos, the cells of this layer contain no pigment.
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This article was originally based on an entry from a public domain edition of Gray\'s Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.
| Sensory system - Visual system - Eye - Retina | |
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| cells | Photoreceptor cells (Cone cell, Rod cell) → (Horizontal cell) → Bipolar cell → (Amacrine cell) → Ganglion cell Giant retinal ganglion cells - Photosensitive ganglion cell - Muller glia |
| layers | Inner limiting membrane - Nerve fiber layer - Ganglion cell layer - Inner plexiform layer - Inner nuclear layer - Outer plexiform layer - Outer nuclear layer - External limiting membrane - Layer of rods and cones - Retinal pigment epithelium |
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