Incidence of tail structure distortions associated with dysplasia of the fibrous sheath in human spermatozoa.

Dysplasia of the fibrous sheath (DFS) is an anomaly found in spermatozoa of severe asthenozoospermic patients. Marked hypertrophy and hyperplasia of the fibrous sheath is the common characteristic. Immunocytochemistry allowed us to visualize the distortions and incidence of tail structure abnormalities associated with this phenotype in six patients; four with a complete form and two with an incomplete form of this pathology previously diagnosed and studied by electron microscopy. Microtubules and fibrous sheaths were studied using monoclonal antibodies against alpha-acetylated tubulin and anti-FSC1 (the major protein component of the fibrous sheath). Mitochondrial sheaths were visualized using the mitochondrion-specific vital dye MitoTracker green FM(TM). Phase contrast and fluorescent microscopy of semen samples showed large numbers of spermatozoa with short, rigid, thick and irregular tails. As expected, anomalous and completely distorted fibrous sheaths, severe alterations of the axonemal microtubules and different patterns of mitochondrial sheath configurations were found. While ultrastructural studies of thin sections allow an in-depth knowledge of the internal organization of the sperm tail, fluorescence labelling of selected sperm components affords a unique view of the whole flagellum including topographical relationships of various organelles. The combination of these different approaches is essential for a comprehensive understanding of this particular pathology.

Pregnancies established through intracytoplasmic sperm injection (ICSI) using spermatozoa with dysplasia of fibrous sheath.

AIM: Dysplasia of the fibrous sheath (DFS) is an anomaly found in asthenozoospermic patients with extremely low or absent motility. In order to determine the efficacy of ICSI in these patients, a retrospective analysis of ICSI results in DFS patients has been done. METHODS: Ten ICSI attempts were performed in 6 patients with diagnosis of Dysplasia of the Fibrous Sheath studied by transmission and scanning electron microscopy. RESULTS: In the cases studied, sperm concentration was (29.62 +/- 18.05) x 10(6)/mL, total motility was 1.14 +/- 1.31%. Progressive motility was 0% except for one case with 0.1% . One hundred and three preovulatory oocytes were obtained and 94 metaphase II oocytes were injected. Sixty-nine of them showed two pronuclei (fertilization rate: 73.4%). Forty-nine embryos were obtained and 34 were transferred (mean: 3.4 embryos per transfer). Five pregnancies were diagnosed by beta-hCG plasma level determinations that resulted to be one preclinical abortion, one clinical abortion and three deliveries. Another pregnancy (ongoing) was achieved from a cryopreserved embryo transfer. CONCLUSION: These results showed that ICSI provides a suitable solution for patients suffering from irreversible sperm defects such as DFS. Nevertheless, it is mandatory to inform couples of possible transmission risks to offspring, which are unknown at present. Only when the etiology of this problem is disclosed, it will be possible to assess the real genetic risk.