Altered ultrastructure of mitochondrial membranes is associated with unexplained asthenozoospermia

". OBJECTIVE: To explore the contribution of an altered structure of sperm mitochondria to human asthenozoospermia.. . DESIGN: A retrospective study.. . SETTING: Andrology Clinic, University of L'Aquila.. . PATIENT(S): Fifteen ejaculates with forward motility (FM) ≥ 50%, and 57 asthenozoospermic ejaculates (FM <50%, sperm vitality >50%), including 14 ejaculates with systematic genetic defects of tail principal piece, and 43 ejaculates with unexplained asthenozoospermia.. . INTERVENTION(S): Fifty sections of tail middle piece (MP) were blindly analyzed by transmission electron microscopy in each ejaculate for normal mitochondrial membrane organization, after exclusion of tails with disrupted cell membranes.. . MAIN OUTCOME MEASURE(S): Percentage of MPs with normal mitochondrial membranes (% normal MPs).. . RESULT(S): Percent normal MPs showed a strong correlation with forward motility. Variation of % normal MPs explained a 45% variation of sperm motility at multivariate linear regression analysis, confirming the strong association between the two parameters in a population including ejaculates with normal motility and with unexplained asthenozoospermia. Percent normal MPs was significantly reduced in severe unexplained asthenozoospermia (FM <10%; n = 16) compared with samples with normal motility (FM ≥ 50%; n = 15); 21% (10.5%-38%) and 68% (52%-73%), respectively.. . CONCLUSION(S): Structural defects in mitochondrial membranes represent a main feature of severe unexplained asthenozoospermia.. . "