part_of adult male endospermatophore adult spermatozoa Fig. 17-16, Fig. 17-18, Fig. 17-20, in Biology of Ticks ISBN:0-19-505910-7. TADS:0000548 TADS:0000548 The fully mature capacitated (differentiated) sperm cells that are capable of migrating up the oviducts to the ovary and fertilizing the oocytes. Spermatozoa undergo capacitation within the endospermatophore within the body of the female (i.e., within the seminal receptacle. The fully mature spermatozoa may reach up to 1000 microns in some tick species . default_namespace