Ultrastructure of the ejaculatory duct region producing the male housefly accessory material

The male accessory material of houseflies is produced by what appears to be one type of cell in the anterior part of the ejaculatory duct. The cells of this part of the ejaculatory duct have an extensive rough endoplasmic reticulum, numerous free ribosomes, and many Golgi complexes. Secretion of the accessory material seems to occur as a mixture of release via individual Golgi vesicles, the splitting off of portions of cytoplasm, and the lysis of entire cells. No evidence was found of replacement of lysed cells. Synthesis of the secretory material is most active soon after emergence and after mating. The material accumulates around the duct lumen between the secretory cells and the intima and passes directly through the intima in being discharged from its storage area.