Clinical characteristics and light and transmission electron microscopic sperm defects of infertile men with persistent unexplained asthenozoospermia

Objective: To determine, with the use of transmission electron microscopy (TEM), the proportion of patients with permanent unexplained asthenozoospermia (<30% motility) who have an abnormality of sperm axonemal and periaxonemal structures. Design: Retrospective study. Setting: A university-affiliate public hospital. Patient(s): Sixty-one infertile men whose semen was submitted to TEM analysis because of persistent unexplained asthenozoospermia. Main Outcome Measure(s): The results of quantitative TEM analysis of the tails of the spermatozoa. Intervention(s): None. Result(s): Based on a comparison with the axonemal anomalies observed in nine fertile control patients, the infertile population was divided into three groups: group I, with no detectable axonemal defects (26.2%); group II, with axonemal anomalies in either the midpiece or the principal piece (29.5%); and group III, with axonemal anomalies in both the midpiece and the principal piece (44.3%). However, defects in the mitochondrial sheath, fibrous sheath, and sperm head (acrosomic and postacrosomic cap) were observed in at least 50%, 30%, and 50%, respectively, of the patients in each group. The proportion of dense fiber anomalies of the midpiece increased significantly from group I to group III. No differences were observed between the three groups in sperm characteristics, anamnesis information, or clinical data. Conclusion(s): In patients with persistent unexplained asthenozoospermia, the frequent association of periaxonemal anomalies with axonemal deficiencies strongly suggests that axonemal deficiencies are not the unique cause of decreased motility. (Fertil Steril(R) 1998;70:297-304. (C)1998 by American Society for Reproductive Medicine.).