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

Spermatogenesis and the structure of the spermatozoon of the frog inte stinal 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 undifferentiat ed spermatogonial cells, with cytoplasm rich in free ribosomes. The ar rangement of the diverse spermatogonic cell populations is similar to those studied in other digeneans. During spermatogenesis the elongatio n and spiralling of nuclear materials occurs synchronously in the late spermatid stage. The G. tigrinum spermatozoon appears to be biflagell ate due to the presence of two filaments. Between the two filaments is an elongated nucleus; these elements fuse to form the monopartite sha ft of the sperm. The spermatozoon of G. tigrinum is characterized by t he presence of an unusually long nucleus that even surpasses the lengt h of the mitochondrion. At almost half the length of the spermatozoon there is sharp rotation between first axial filament, mitochondrion an d the nucleus. Both the axial filaments show 9+1 arrangement of axonem al units throughout the spermatozoon.