A survey of the ultrastructural defects associated with absent or impaired human sperm motility

The sperm tails of 400 patients having absent or impaired sperm motility were examined by electron microscopy. A wide variety of fine-structural defects were observed although all of the patients fell into clearly defined groups. Total or partial dynein arm deficiency was observed in 12 patients (3%). Ninety-one patients (23%) had sperm with a spectrum of fine-structural defects, whereas 90 patients (23%) were necrospermic. Subjects with low motility, but with at least a few tails of normal structure, had a 5% pregnancy rate, whereas those patients with similar overall motility, but in whom no normal sperm were seen, produced no pregnancies. The results confirm the importance of making an electron microscopical examination of the sperm of patients with asthenozoospermia.