Current understanding on the role of retinal pigment epithelium and its pigmentation

Pigment Cell Res. 1999 Aug;12(4):219-36. doi: 10.1111/j.1600-0749.1999.tb00755.x.


Retinal pigment epithelium (RPE) is a monolayer of cuboidal cells that is strategically placed between the rod and cone photoreceptors and the vascular bed of the choriocapillaris. It has many important functions, such as phagocytic uptake and breakdown of the shedded photoreceptor membranes, uptake, processing, transport and release of vitamin A (retinol), setting up the ion gradients within the interphotoreceptor matrix, building up the blood-retina barrier, and providing all transport from blood to the retina and back. This short review focuses on the role of the pigment granules in RPE. Although the biology of the pigment granules has been neglected in the past, they do seem to be involved in many important functions, such as protection from oxidative stress, detoxification of peroxides, and binding of zinc and drugs, and, therefore, serve as a versatile partner of the RPE cell. Melanin plays a role in the development of the fovea and routing of optic nerves. New findings show that the melanin granules are connected to the lysosomal degradation pathway. Most of these functions are not yet understood. Deficit of melanin pigment is associated with age-related macula degeneration, the leading cause of blindness.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Age Factors
  • Albinism / genetics
  • Albinism, Oculocutaneous / genetics
  • Albinism, Oculocutaneous / physiopathology
  • Angelman Syndrome / genetics
  • Angelman Syndrome / physiopathology
  • Animals
  • Chediak-Higashi Syndrome / genetics
  • Chediak-Higashi Syndrome / physiopathology
  • Eye Diseases / genetics*
  • Eye Diseases / metabolism
  • Eye Diseases / physiopathology*
  • Humans
  • Lipofuscin / physiology
  • Macular Degeneration / genetics
  • Macular Degeneration / physiopathology
  • Melanins / physiology*
  • Melanosomes / ultrastructure
  • Oxidative Stress
  • Photoreceptor Cells, Vertebrate / physiology
  • Pigment Epithelium of Eye / physiology*
  • Pigments, Biological / physiology
  • Zinc / metabolism


  • Lipofuscin
  • Melanins
  • Pigments, Biological
  • Zinc