Fine structure of the retinal pigment epithelium ofOreochromis niloticus L. (Cichlidae; Teleostei) in light- and dark-adaptation

Autor: Stephen A. Smith, Bonnie J. Smith, Charlie R. Braekevelt
Rok vydání: 1998
Předmět:
Zdroj: The Anatomical Record. 252:444-452
ISSN: 1097-0185
0003-276X
DOI: 10.1002/(sici)1097-0185(199811)252:3<444::aid-ar12>3.0.co;2-4
Popis: The fine structure of the retinal pigment epithelium (RPE) of the cichlid Oreochromis niloticus was investigated in both light- and dark-adaptation. The eyes of four light-adapted and from four dark-adapted O. niloticus were fixed routinely for light and transmission electron microscopy. The RPE consisted of a single layer of columnar cells showing minimal basal infolding but plentiful apical processes that in light-adaptation interdigitated with the photoreceptor outer segments. The epithelial cells were joined by a series of basally-located tight junctions. These cells showed a large vesicular nucleus, plentiful smooth endoplasmic reticulum and polysomes, but only small amounts of rough endoplasmic reticulum. Phagosomes, lysosome-like bodies, lipid droplets, and myeloid bodies were observed. The choriocapillaris was a single layer of large-caliber capillaries, and Bruch's membrane (complexus basalis) was a trilaminate structure typical of teleosts. The RPE melanosomes moved basally (sclerally) in dark-adaptation and apically (vitreally) during light-adaptation. Other morphological features which changed at least to some degree during retinomotor responses were: the location of the RPE nucleus; the location and electron density of the mitochondria; and the location, number, and size of the myeloid bodies. A number of unique morphological changes take place within the RPE cells of this species during the circadian cycle in addition to the movement of melanosomes characterized in other vertebrates.
Databáze: OpenAIRE
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