[Ultrastructural changes in boar spermatozoa during freezing-thawing].

Using electron microscopy, no significant alteration were revealed in the boar spermatozoa suspended for 0.5-1 hour in the medium containing protective stuff except some desquamation and disruption in the spermatozoon head region. Similar picture was seen after a 3 hours' treatment in the medium. However, after freezing (-196 degrees C) and thawing more significant structural changes appear, at first part, in the head membrane structures. In addition, fragmentation and swelling of mitochondria is observed possibly accounting for the lack of spermatozoa motility after thawing.