Publication: Development of the retinal tapetum lucidum
of the walleye (Stizostedion vitreum vitreum)
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Date
1989
Authors
Braekevelt, Charlie R. ; Mclntyre, D. B. ; Ward, F. J.
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Publisher
Murcia : F. Hernández
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DOI
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info:eu-repo/semantics/article
Description
Abstract
The development of the retinal tapetum
lucidum within the cells of the retinal pigment epithelium
(RPE) has been investigated by both light and electron
microscopy in the walleye (Stizostedion vitreum vitreum)
in specimens ranging in total length from 25-140 mm. In
addition changes in the arrangement of the photoreceptors
(both rods and cones) in both light and darkadaptation
have also been studied. At 25 mm no
evidence of a tapetum is present. At about 30 mm it
makes its initial appearance as granular bodies formed
within the apical smooth endoplasmic reticulum (SER)
cisternae of the RPE cells in the superior temporal
fundus. The developing tapetum then spreads
peripherally and continues to thicken in existing areas.
By 90 mm it is well established throughout the fundus but
always appears better developed in the superior fundus.
By 125-140 mm it is essentially adult in appearance. At
60-70 mm the rods and cones begin to form bundles
producing macroreceptors of 20-30 photoreceptors. In
dark-adaptation the rod bundles are retracted and have
one or more cone cells centrally located in each bundle,
with the bundles separated from one another by
melanosomes. Initially when no tapetal material is
present, post-larva1 walleye are positively phototactic
and feed on zooplankton. In the adult condition when a
tapetum lucidum and large macroreceptors are present,
the walleye is negatively phototactic and feeds almost
exclusively on larger organisms such as other fish.
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