A specialized organelle found in the photoreceptor cells of an ommatidium (q.v.). In Drosophila each rhabdomere is composed of ∼60,000 tightly packed microvilli which expand the membrane surface to accommodate hundreds of millions of molecules of rhodopsin (q.v.). Each rhabdomere functions like the discs in the outer segments of the photoreceptor cells of the vertebrate retina (q.v.). See microvillus.
Subjects: Genetics and Genomics.