Ultrastructural analysis of five patients with total sperm immotility.

Asthenozoospermia has been related to structural defects of the sperm flagellum. However, few reports have studied in detail the ultrastructure of sperm with total immotility. We present an ultrastructural study of sperm from five patients with total sperm immotility, four due to dysplasia of the fibrous sheath (DFS) and one with situs-inversus. Of the four patients with DFS, three cases presented a hypertrophic and hyperplastic fibrous sheath that invaded the midpiece space, absence of the annulus, and a short midpiece containing a few disorganized and pale mitochondria. Of these cases, two presented absence of the central complex and radial spokes; another additionally presented absence of dynein arms and nexin bridges; and the other patient presented an intact annulus with a dysplastic fibrous sheath restricted to the principal piece with disorganized microtubule doublets. The patient with situs-inversus presented severe respiratory symptoms, with absence of dynein arms and nexin bridges. In conclusion, we present three cases with DFS associated with total sperm immotility, abnormal mitochondria, and absence of the annulus, central pair complex and radial spokes, of which one had in addition absence of dynein arms and nexin bridges. We also describe a patient, with total sperm immotility and a different presentation of DFS, as the annulus was present and the dysplastic fibrous sheath was restricted to the principal piece. These findings thus confirm the heterogeneity of the DFS condition. The changes observed in the patient with situs-inversus also further support previous observations.