Membrane formations in the pineal cells of the teleost Gambusia affinis.

Highly organized membrane formations in the cytoplasm of photoreceptor and supporting cells of the pineal organ of Gambusia affinis are described. These membranous structures show different characteristics depending on the cell type where they are located. Some of the morphological characteristics of these membranous formations are similar to those of myeloid bodies, but their presence in the photoreceptor cells raises some doubt about their being myeloid bodies. The three-dimensional interpretation of these structures is discussed.