Round-headed human spermatozoa.
Ultrastructural investigation of two cases of round-headed spermatozoa from human ejaculates revealed the existence of two different pathomorphogenetic types. Case 1 represented round-headed spermatozoa of the Schirren and Holstein type caused by loss of the abnormally formed acrosome during spermiogenesis and the missing nuclear transformation. In case 2 a primary maturing inhibition was responsible for the round-headed feature of the spermatozoa; the normally flattened, conical nucleus and acrosomal cap were surrounded by huge droplets of ample cytoplasm. Secondary degenerative changes contributed to the decreased motility of these round-headed spermatozoa. Therapeutic trials for this oligospermic patient showed that an increase in cell count to values in the low-normal range and a drastic reduction in the percentage of round-headed cells (from 80% to 47%) could be achieved. The Schirren and Holstein type, however, must be regarded as absolutely infertile due to the absence of an acrosome and its intrinsic enzymes.