Effects of Cryopreservation on the Ultrastructure of Human Testicular Sperm

Objective To investigate effects of cryopreservation on changes of the ultrastructure of human testicular sperm and evaluate the efficacy of cryopreserving testicular tissue as a source of sperm for assisted reproduction. Methods Testicular biopsy tissues were obtained from infertile patients (n=12) with obstructive azoospermia and cryopreserved. Testicular sperm motility was observed after in vitro culture procedure. The ultrastructure of testicular sperm (n=6) was examined by transmission electron microscope. Results After cryopreservation, 10 biopsy tissues frozen revealed motile sperm, and 2 samples showed non-motile sperm. Some testicular sperm in frozen-thawed group had normal morphology in fine structures. Sperm head in frozen-thawed tissue showed a proportion of nuclei with more electron-dense granules of chromatin. In a few frozen-thawed sperm heads, formation of vesicles and degeneration were observed. The frozen-thawed testicular sperm frequently showed swollen or/and ruptured of the plasma membrane and acrosome membranes. Conclusion Cryopreservation of testicular tissue is simple and efficacious for testicular sperm extraction. And the freezing-thawing procedure of testicular tissue causes damage to ultrastructural morphology of human testicular sperm.