ULTRASTRUCTURAL-STUDY ON SPERMATOGENESIS IN GANEO-TIGRINUM, AN INTESTINAL TREMATODE OF RANA-TIGRINA

Spermatogenesis and the structure of the spermatozoon of the frog intestinal fluke, Ganeo tigrinum has been examined by electron microscopy. Each testis is covered by a tunica consisting of sustentacular cells and fibrous material. internally the testis is lined by undifferentiated spermatogonial cells, with cytoplasm rich in free ribosomes. The arrangement of the diverse spermatogonic cell populations is similar to those studied in other digeneans. During spermatogenesis the elongation and spiralling of nuclear materials occurs synchronously in the late spermatid stage. The G. tigrinum spermatozoon appears to be biflagellate due to the presence of two filaments. Between the two filaments is an elongated nucleus; these elements fuse to form the monopartite shaft of the sperm. The spermatozoon of G. tigrinum is characterized by the presence of an unusually long nucleus that even surpasses the length of the mitochondrion. At almost half the length of the spermatozoon there is sharp rotation between first axial filament, mitochondrion and the nucleus. Both the axial filaments show 9+1 arrangement of axonemal units throughout the spermatozoon.