The effect of light and light deprivation upon the ultrastructure of the larval mosquito eye. II. The rhabdom

Abstract

AbstractThe surface area of the rhabdom membrane is two to three times greater in mosquito larvae grown in darkness than it is in larvae grown in light. Moreover, light adapted rhabdom microvilli are covered with a surface coat and produce coated vesicles, while the light deprived rhabdom has no coat and does not form coated vesicles. The light adapted microvilli are held together by septate desmosomes; the light deprived microvilli appear to be packed loosely together.When a light deprived rhabdom is first exposed to light, the membranes of adjacent microvilli rapidly fuse so that the intervillous space is lost. During the next several hours the rhabdom reorganizes to the light adapted state. The intervillous space reopens. The area of the rhabdom membrane diminishes. The coat forms, and coated vesicles are produced in large numbers. This light induced transformation is of interest because of the presumed photoreceptive function of the rhabdom.