Spermatophore formation and sperm transfer in Ornithodoros ticks.

In seven species of Ornithodoros and two species of Argas ticks the spermatophore is formed outside the male body in three consecutive stages: (i) the outer bulb, the ectospermatophore, is formed; (ii) it is filled with sperm; and (iii) the inner capsules, the endo-spermatophore, are extruded into the ecto-spermatophore. The morphologies of the ecto-spermatophore and the endo-spermatophore are related to their biological functions. Eversion and evagination of the endo-spermatophore after deposition of the spermatophore on the female genital opening, as well as transfer of sperm from ecto-spermatophore to endo-spermatophore, are described.