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 ge nital tract of Eyprepocnemis plorans (Orthoptera: Acrididae). In this species the spermatheca consists of a long duct with two terminal dive rticula: a preapical one with a U-bend and a straight apical one. Afte r copulation the spermatozoa reach the diverticula where they undergo a peculiar uncoating process which leads to the complete removal of th e glycocalyx. This prepares the spermatozoa to interact with the femal e gametes. A different role is performed by the two diverticula in spe rm storage. In the preapical one most sperm are stored until fertiliza tion of the egg; in the apical diverticulum a limited number of sperma tozoa are stored but most are progressively dismantled. These modifica tions may reduce any excess of spermatozoa or operate a mechanism of s election, aiming to favour sperm from the last mating.