PATERNAL PRODUCTS AND BY-PRODUCTS IN DROSOPHILA DEVELOPMENT

Tails of fertilizing spermatozoa persist throughout embryogenesis in D rosophila species and can be observed within the midguts of larvae aft er hatching. Throughout development, sperm proteins slowly diffuse or are stripped from the giant sperm tail residing within the embryo's an terior end. The shape and position of the sperm within the embryo are regulated such that, during organ formation, the unused portion of the sperm is enveloped by the developing midgut. This persistent, paterna lly derived structure is composed of the sperm's mitochondrial derivat ives and appears to be defaecated by the larva soon after hatching. Th ese complex sperm-egg interactions may represent mechanisms to avoid i ntragenomic conflict by ensuring strictly maternal inheritance of mito chondrial DNA (mtDNA).