A new observation on spermateleosis in ticks.

The first phase of spermiogenesis in argasid and ixodid ticks is described. The inner core of the spermatid passes through the outer sheath so that speriogenesis is permitted to follow its course. The outer sheath is not ruptured in the process, but a well-defined operculum opens to let the inner core through. The opening of the operculum is a clear-cut indication of the beginning of spermiogenesis. In the examined species speriogenesis begins in Argasidae when the male transfers the spermatophore to the female genital opening, whereas in Ixodidae it starts only after the endospermatophore has reached the female genital tract.