Retinal pigment epithelium
Name = Retinal pigment epithelium
Latin = p. pigmentosa retinae
GraySubject = 225
GrayPage = 1016
Caption = Section of
retina. (Pigmented layer labeled at bottom right.)
Caption2 = Plan of retinal neurons. (Pigmented layer labeled at bottom right.)
DorlandsPre = p_07
DorlandsSuf = 12617535
The retinal pigment epithelium (RPE) is the
pigmented cell layer just outside the neurosensory retinathat nourishes retinal visual cells, and is firmly attached to the underlying choroidand overlying retinal visual cells.cite book |author=Cassin, B. and Solomon, S. |title=Dictionary of eye terminology |publisher=Triad Pub. Co |location=Gainesville, Fla |year=2001 |pages= |isbn=0-937404-63-2 |oclc= |doi=] [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.]
The RPE was known in the 18th and 19th centuries as the pigmentum nigrum, referring to the observation that the RPE is dark (black in many animals, brown in humans); and as the tapetum nigrum, referring to the observation that in animals with a
tapetum lucidum, in the region of the tapetum lucidum the RPE is not pigmented. [cite book
author=Coscas, Gabriel and Felice Cardillo Piccolino
title=Retinal Pigment Epithelium and Macular Diseases
pages= |isbn=0792351444 |oclc= |doi=]
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
phagocytosisof the outer segment of photoreceptor cells and it is also involved in the vitamin Acycle where it isomerizes all trans retinolto 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 amino acid,
ascorbic acidand D-glucose while remaining a tight barrier to choroidal blood borne substances. Homeostasisof the ionic environment is maintained by a delicate transport exchange system.
In the eyes of
albinos, the cells of this layer contain no pigment. Dysfunction of the RPE is found in Age-Related Macular Degenerationand Retinitis Pigmentosa.
Wikimedia Foundation. 2010.
Look at other dictionaries:
Retinal pigment epithelium — The pigment cell layer that nourishes the retinal cells. The retinal pigment epithelium is located just outside the retina and is attached to what is called the choroid, a layer filled with blood vessels that nourish the retina. * * * (RPE)… … Medical dictionary
retinal pigment layer — a single cell layer of pigmented epithelium covering the neural retina and developing from the outer of the two layers of the optic cup … Dictionary of ichthyology
Iris pigment epithelium — Anatomy The iris pigment epithelium (IPE) is a two cell thick layer of cuboidal cells lying behind the iris. Both layers are jet black due to the numerous large melanosomes which pack the cytoplasm of each cell. Towards the central axis, the IPE… … Wikipedia
Retinal detachment — Classification and external resources Slit lamp photograph showing retinal detachment. ICD … Wikipedia
Retinal G protein coupled receptor — Retinal G protein coupled receptor, also known as RGR, is a human gene.cite web | title = Entrez Gene: RGR retinal G protein coupled receptor| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene Cmd=ShowDetailView TermToSearch=5995| accessdate … Wikipedia
Retinal detachment — A separation of the retina from its connection at the back of the eye. The separation usually results from a tear (that is, a rent or rip, not a tear drop) in the retina. The tear often occurs when the vitreous gel pulls loose or separates from… … Medical dictionary
pigment epitheliopathy — acute posterior multifocal placoid pigment epitheliopathy (APMPPE): an inflammatory disease of the retinal pigment epithelium (RPE; see retina), characterized by the presence of multiple cream coloured irregular lesions scattered in the posterior … Medical dictionary
pigment epitheliopathy — acute posterior multifocal placoid pigment epitheliopathy (APMPPE): an inflammatory disease of the retinal pigment epithelium (RPE; see retina), characterized by the presence of multiple cream coloured irregular lesions scattered in the posterior … The new mediacal dictionary
retinal detachment — detached retina separation of the inner nervous layer of the retina from the outer pigmented layer (retinal pigment epithelium) to which it is attached. It commonly occurs when one or more holes in the retina allow fluid from the vitreous cavity… … The new mediacal dictionary
Epithelium — The outside layer of cells that covers all the free, open surfaces of the body including the skin, and mucous membranes that communicate with the outside of the body. By contrast the endothelium is the layer of cells lining the closed internal… … Medical dictionary