Figure 19: TEM of L.S. of spermatozoon of O. niloticus of LM showing a change in the chromatin shape of the nucleus (N), Flagellum (F) and side fins (SF), Notice the presence of vacuoles (V), the implantation fossa (IF) containing the proximal centriole (PC), distal centriole and the basal segment of the flagellum. (X 30000).