A case of severe asthenozoospermia: a novel sperm tail defect of possible genetic origin identified by electron microscopy and immunocytochemistry

Abstract

To characterize a novel flagellar defect involving 98% of sperm tails. Case report. Interdepartmental Centre for Research and Therapy of Male Infertility, Siena, Italy. A 45-year-old infertile man with severe asthenozoospermia. Family history, physical examination, hormonal analysis, microbial assays, semen analysis, transmission and scanning electron microscopy, tubulin distribution investigated by immunocytochemistry, fluorescence in situ hybridization (FISH) for chromosomes 9, 16, 18, X, and Y. Flagellar abnormalities detected by microscopical methods. An apparent heterogeneity was observed: extremely elongated tails prone to ruptures; coiled tails at different levels with a strongly rolled axoneme or with a curl in the final flagellar segment; and V-shaped, isolated, bent tails. Transmission electron microscopy revealed the presence of normal heads, disorganized flagellar structures, and dynein deficiency. The FISH analysis was normal. We report a new sperm defect, characterized by abnormal elongation of the tail, which was prone to ruptures at different levels, concomitant with coiled tails, which were impossible to measure in length. This defect remained constant in different examined ejaculates and applied to the entire sperm population of a sterile man, the son of first-degree cousins, indicating a potential genetic origin.