Migration and motility of spermatozoa in the female reproductive tract of the soft tick Ornithodoros moubata (Acari, Argasidae)

Abstract

SUMMARYThe spermatozoa of ticks are anomalous in many respects: they are very large, cytoplasm-rich cells which lack a flagellum but move with a peculiar gliding motility. Their metamorphosis after deposition in the female has been well documented, but many of the subsequent events in the career of the spermatozoa are controversial or poorly documented. Our observations of motility imply that the many types of motility that have been reported (up to 5 different types in several reports) can be reduced to 2 apparently independent types of active motility: (1) gliding motility generated along the whole spermatozoon and (2) contortions of the anterior tip of the head. These types of motility appear as a consequence of sperm maturation after transfer to the female, but only become pronounced if the female has taken a recent bloodmeal. A consequence of this enhanced gliding motility after feeding is the movement of the spermatozoa out of the naturally ruptured neck of the spermatophore and up the female genital tract. This occurs without any apparent assistance from the female's musculature and likely is the prime mechanism of movement of the spermatozoa to the site of fertilization.