[The cytostructure and morphogenesis of the rod outer segments]

This paper is a review discussing the cytomolecular structure of the rods, retinal photoreceptor cells, whose structural uniformity contributed to the progress in studies of their structure and morphogenesis in the vertebrate eye. Recent studies of protein and phospholipid metabolism in the rod inner segment have been reviewed. The structure of the outer segment connecting cilium is discussed with reference to the TEM and SEM, freeze-fracture, biochemical and immunological studies. The membranes of the rod outer segment undergo continuous renewal. The use of fine biochemical methods permitted to find differences in the structure of the plasma membrane surrounding the rod outer segment and the membrane discs, that fill this segment. Recent hypotheses dealing with morphogenesis of the rod outer segment membrane discs are also discussed. Special attention is paid to actin and myosin, as well as a small transient fraction of galactose-containing rhodopsin.