Ultrastructure of the spermatozoon of Silurus soldatovi

The spermatozoon of Silurus soldatovi consists of head, middle piece and tail. The head is like a globe or an ellipsoid. There is no acrosome at the anterior end of the nuclears, whereas there is an implatation fossa at the posterior end of the nuclears, within which the chromatin is dense and nuclear vacuole(NV) is existent.The middle piece consists of the centrioles and the sleeve. Two single hemi global centrioles are opposite to each other,thus constituting the proximal centriole,an empty globe,which is nucleus dense. The distal centriole is like a bell, with its top connecting to the proximal centriole and with the entrance of its bottom connecting to the axoneme of the sperm tail. The sleeve, which is rich in mitochondria and vesicles, is connected to the posterior end of the nucleus. The main structure of the tail is axoneme,which is the structure of a typical “9+2”. There are no vesicles nor other cell organelles in the tail. The outer surface of the tail is quite smooth without fin like structure.