Ultrastructural study of the decapitated sperm defect in an infertile man

Abstract
An infertile man presented a spermiogram in which 100% of the spermatozoa displayed separation of head from tail at the level of the proximal centriole. Most tails were normally structured and ended anteriorly with the proximal centriole covered by a continuous plasma membrane. In a small percentage of tails, a rudimentary connecting piece was surrounded by a minute cytoplasmic mass and the middle piece was missing, while the chromatoid body and the spindle-shaped body were still present. A few tails had a large cytoplasmic mass surrounding either regular connecting and middle pieces or a rudimentary connecting piece continuous with the main piece. Tails of the 1st type had good forward motility, although the pattern of movement appeared altered. The other types were immotile or motile but without forward progression. In the loose heads the implantation fossa failed to differentiate. The separation of heads from tails appeared to be the result of a specific morphogenetic defect and took place at different stages of spermatid differentiation, giving rise to the structurally different types of tails.