Ultrastructure of spermiogenesis and the spermatozoon of Paramphistomum microbothrium (Fischoeder 1901; Digenea, Paramphistomidae), a parasite of Bos taurus in Senegal.

The ultrastructural study of spermiogenesis and the spermatozoon of Paramphistomum microbothrium gave evidence of some characteristics of this digenean. The intercentriolar body located between two striated roots and two centrioles exhibits a symmetric plane. The two external bands of this intercentriolar body are made up of a line of granules. The striated roots are about 3.7-microm long. During spermiogenesis, a flagellar rotation of 90 degrees is described. The spermatozoon is characterized in its anterior part by the existence of external ornamentations and a lateral expansion exhibiting a "spine-like body." Such a spine-like body has never been described before in a digenean. The region II of the spermatozoon is asymmetrical and also characterized by the absence of mitochondrion. The posterior end of this spermatozoon exhibits a nucleus and a few microtubules.