[Myeloid bodies of the retinal pigment epithelium in vertebrates]

After the hypothesis of Porter and Yamada about the photoreceptive role of myeloid bodies of the vertebrate pigment epithelium, we have pointed out the fine ultrastructure of these organelles: they consist of piles of flattened saccules, with a lipidic content, and linked together by an inter-saccular cement. They are not like Golgi bodies: they do not content glycoprotein. They must be discarded from phagosomes, which are membrane-bounded and content acid phosphatase activity. An oxido-reductive activity cannot been demonstrated at their level, similar to that observed on the rod outer segments. Freeze-etching does not show peculair organization on their fracture faces. They represent a special organization of the endoplasmic reticulum which seems to have a function in the metabolism of visual pigments in certain species of animals, the retina of which is avascular.