Reversible, light-screening pigment of elasmobranch eyes: chemical identity with melanin.
There lies directly beneath the tapetum lucidum, in the eyes of many elasmobranch fishes, a layer of darkly pigmented choroid cells which, in bright light, extend individual strands that aggregate to form a dark, compound curtain which shields the reflecting tapetal cells. This process is reversed in dim light or in darkness; the tapetum is exposed and visual sensitivity presumably Increased. The black choroid pigment has been isolated, analyzed, and shown to possess the properties of melanin.
D000818:Animals; D011232:Chemical Precipitation; D002623:Chemistry Techniques, Analytical; D002829:Choroid / Q000378:metabolism*; D005123:Eye / Q000378:metabolism*; D005399:Fishes / Q000378:metabolism*; D066298:In Vitro Techniques; D008543:Melanins / Q000378:metabolism*
D008543:Melanins