Fig. 1.

During mating in Drosophila, sperm leave the male’s seminal vesicles and descend through the ejaculatory duct, where they mix with SFPs from the accessory glands, ejaculatory duct, and ejaculatory bulb. This mixing continues after insemination within the female’s bursa, where sperm also mix with FRT-derived proteins. Sperm are then stored in the seminal receptacle or paired spermathecae or they are ejected from the female along with the mating plug. Sperm therefore encounter many environments during their movement through the male and FRTs. Reproductive organs highlighted in bold indicate where sperm samples in this study were collected to characterize the sperm proteome across the major stages of posttesticular maturation, namely, the 1) seminal vesicles, 2) bursa, and 3) sperm-storage organs. Image credit: illustration by Siyuan Cong (Syracuse University, Syracuse, NY) and Ben Woolsey (B+Artworks, Philadelphia, PA).