'Disk shedding' in the cone outer segments of the teleost, Poecilia reticulata P

Electron microscopical observations show that the cones in the retina of the diurnal Poecilia reticulata shed their membranous outer segment disks. This occurs at the side of the disk which is open to the extracellular space. Shedding is observed in single and twin cones and occurs at any level of the outer segment. The disks are not discarded in packages or as single disks, but are shed in small vesicular portions. This mode of 'disk shedding' may explain why in cone outer segments radioactively labelled replacement protein is diffusely distributed.