Retinal fine structure in the European eel Anguilla anguilla. VII. Pigment epithelium of the sexually mature silver eel stage.
This report describes the morphology of the retinal pigment epithelium (RPE), Bruch's membrane and choriocapillaris in the sexually mature silver eel and compares these observations with previous descriptions of this region in the glass, yellow and sexually immature silver eel stages of the lengthy life cycle of the European eel. The retinal epithelium in the sexually mature silver eel is a single layer of cuboidal to squamous cells joined laterally by apically located cell junctions. Both the basal (scleral) and lateral borders of the epithelial cells are relatively smooth while apically (vitreally) numerous processes enclose a photoreceptor inner and outer segments. The epithelial cells contain abundant profiles of smooth endoplasmic reticulum (SER), numerous small mitochondria and melanosomes and a single pleomorphic, vesicular nucleus. Lipid droplets are large and abundant at this stage. Myeloid bodies, phagosomes and lysosomes are also present. Rough endoplasmic reticulum (RER) is not plentiful. Wandering phagocytes are a constant feature of this region. Bruch's membrane is still trilaminate but is now much thicker than at any previous stage. The choriocapillaris remains as a single layer of fenestrated capillaries adjacent to Bruch's membrane. The stratum argenteum is still present in the choroid and separated from the RPE by pigmented cells. Single cells presumed to be from the stratum argenteum are, however, often located close to Bruch's membrane.
Braekevelt
C R
CR
Department of Anatomy, University of Manitoba, Winnipeg, Canada.
D000811:Anguilla / Q000033:anatomy & histology* / Q000254:growth & development; D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D007365:Intercellular Junctions / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D010857:Pigment Epithelium of Eye / Q000648:ultrastructure*; D012160:Retina / Q000648:ultrastructure*