New fibrous sheath anomaly in spermatozoa of men with consanguinity.

The cause of the sperm motility impairment was investigated in infertile men. Case report. University-based andrology laboratory. Two unrelated consanguineous patients. None. The sperm flagella lengths were measured using quantitative analysis software and their ultrastructural anomalies were quantitatively recorded. A total of 67.5% of the flagella were truncated, and 100% lacked the medium region of the ribs of the fibrous sheath. The data suggested a morphogenetic anomaly at the stage where rib precursors are formed during spermiogenesis. The consanguinity of these patients suggested a genetic origin for this newly discovered anomaly of the human sperm's fibrous sheath. The family tree appears to indicate an autosomal recessive inheritance.