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On the eye of the Goldeye Hiodon alosoides (Teleostei: Hiodontidae)
Author(s) -
Best A. C. G.,
Nicol J. A. C.
Publication year - 1979
Publication title -
journal of zoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0952-8369
DOI - 10.1111/j.1469-7998.1979.tb03418.x
Subject(s) - biology , anatomy , bundle , materials science , composite material
In the eye of the Goldeye the photoreceptors are arranged in bundles and the pigment epithelium contains a massive reflector or tapetum lucidum. Photoreceptor bundles are arranged in parallel rows, the bundles alternating in position from row to row. Each bundle contains about 60 photoreceptors, of which 30 or so are cones. Rod outer segments lie in the scleral half of the outer retinal region of the light‐adapted eye. Processes of the pigment epithelium cells extend vitread almost to the external limiting membrane; they envelop the bundles of rods and cones, and a ring of four processes surrounds each bundle. A process contains two kinds of reflecting crystals (composed of uric acid). A large part of the epithelium cell is packed with small disc‐shaped crystals (crystallites) enclosed in thin membranes; the tip of the process, in the region of the photoreceptor bundle, contains orderly arrays of small rod‐shaped crystals (rodlets). It is suggested that the crystallites form a diffuse reflector backscattering light into the rods; and that the rodlets reflect light regularly from their surfaces into the photoreceptor bundles. In the light‐adapted state, rods are enveloped by pigment and crystallites. The organization is compared with that of other fishes that have photoreceptors in bundles (grouped retinae) and tapeta lucida.