Dissociated centriole development as a cause of spermatid malformation in man.

Ultrastructural study of a testicular biopsy from an infertile man with decapitated spermatozoa revealed a hitherto undescribed type of malformation. It was caused by a dissociation between the proximal and distal centrioles during the first steps of spermatid differentiation. The disconnection probably occurred because of the lack of striated columns in the connecting piece. Up to 40% of the separately developed and released tails showed a normal motility in the ejaculate.