Ultrastructural changes in sperm of eyprepocnemis plorans (Charpentier) (orthoptera: Acrididae) during storage of gametes in female genital tract

We studied the sperm changes occurring during storage in the female genital tract of Eyprepocnemis plorans (Orthoptera: Acrididae). In this species the spermatheca consists of a long duct with two terminal diverticula: a preapical one with a U-bend and a straight apical one. After copulation the spermatozoa reach the diverticula where they undergo a peculiar uncoating process which leads to the complete re mo val of the glycocalyx. This prepares the spermatozoa to interact with the female gametes. A different role is performed by the two diverticula in sperm storage. In the preapical one most sperm are stored until fertilization of the egg; in the apical diverticulum a limited number of spermatozoa are stored but most are progressively dismantled. These modifications may reduce any excess of spermatozoa or operate a mechanism of selection, aiming to favour sperm from the last mating.