STRUCTURE AND ULTRASTRUCTURE OF THE MALE REPRODUCTIVE SYSTEM IN DROSOPHILA MELANOGASTER MEIG

SUMMARY The structure of the genital duct and accessory glands of the male reproductive system in Drosophila melanogaster was studied by means of phase-contrast and polarized-light microscopes, their ultrastructure being investigated with the electron microscope. Reproductive systems from adult virgins of the Varese wild strain were used as basic material. The results were compared systematically with those from reproductive system of insects of various ages, of insects examined at different times during and after mating and of sterile mutant strains. The most original results relate to: i. the presence of a striated muscle layer whose organization in the individual portions of the reproductive system appears closely related to individual functional activities. Of particular interest is the presence of sphincteric valves between the unpaired deferent duct and the anterior ejaculatory duct. ii. The presence of an unpaired portion connecting the paired vasa deferentia. iii. The peculiar junctions of the acc...