[Sperm metabolism, sperm vitality and cryopreservation]

Out of publications of the last two years some one concerning cryopreservation with clinical-practical relevance were reviewed: Storage at -80 degrees C caused different alterations of activity of the intracellular enzymes. The glucose-6-phosphate-dehydrogenase is the first enzyme which leaves the cell at damage of the cellular membrane. The intracellular concentration of ATP is decreased and the AMP/ADP-rate is increased by the cryopreservation. The cryopreserving process seems to cause an activation of acrosomal proteases of spermatozoa. The damage of cells by cryopreservation is a result of the disturbance of the integrity of membrane and of the loss of ATP and Mg++. Stimulators of spermatozoal motility (caffeine, kallikrein) as a constituent of the cryopreserving medium do not increase the fertilizing capacity of the cryopreserved spermatozoa. Investigations using vitale radiolabelled spermatozoa showed a rate of 4:3 between fresh and cryopreserved spermatozoa in vivo in the upper female genital tract. The penetration test with zona-free hamster oocytes does not allow a prognosis of cryotolerance of the cells. A correlation between rate of penetration and spermiogram is unsure. The cryopreservation of oocytes and embryos is practicable.