Retinal fine structure in the European eel Anguilla anguilla. III. Pigment epithelium of the yellow eel stage.
The catadromous migrations of the European eel (Anguilla anguilla) are accompanied by a number of morphological and biochemical alterations within the visual system. This report describes the morphology of the retinal pigment epithelium, choriocapillaris and Bruch's membrane of the yellow eel and forms the third in a series describing the morphological changes in the retina of the eel during its life cycle. The retinal epithelium of the yellow eel stage consists of a single layer of cuboidal cells joined laterally by tight junctions. Apically, numerous processes enclose photoreceptor cells while basally and laterally the cell borders are relatively smooth. Internally the epithelial cells display abundant smooth endoplasmic reticulum, mitochondria, melanosomes, phagosomes and myeloid bodies. Rough endoplasmic reticulum, polysomes and Golgi zones are present but not plentiful. The nucleus is pleiomorphic and basally located. Bruch's membrane (complexus basalis) is trilaminate. The choriocapillaris is typically fenestrated facing the retina. A stratum argenteum is present in the outer choroid and wandering phagocytes are noted at the retinal epithelium-photoreceptor interface.
D000811:Anguilla / Q000033:anatomy & histology* / Q000254:growth & development; D000818:Animals; D008854:Microscopy, Electron; D009940:Organoids / Q000648:ultrastructure; D010857:Pigment Epithelium of Eye / Q000648:ultrastructure*; D012160:Retina / Q000648:ultrastructure*