HYALURONIDASE ACTIVITY IN HUMAN SEMEN - CORRELATION WITH FERTILIZATION IN-VITRO

Objectives: To characterize the relationship between hyaluronidase act ivity and the currently used methods of assessing sperm function and t o determine whether the measurement of hyaluronidase activity can prov ide a reliable index of sperm fertilizing capacity in man. Design: Non randomized prospective study. Setting: Tertiary referral IVF and andro logy clinics affiliated with the University of Toronto. Subjects: Four hundred eight samples were collected, 248 from men undergoing investi gation in andrology and fertility clinics and 160 from men participati ng in an IVF program. Interventions: Semen samples were treated with N P-40 in buffer to extract hyaluronidase and applied to a circular well cut into a petri dish containing a mixture of hyaluronic acid and aga r. Enzyme activity was assessed by measuring the area of substrate hyd rolysis. Results: Significant positive correlations were found between hyaluronidase activity and sperm concentration, motility, and the per centage of sperm with normal morphology in the studied samples. In the IVF samples, hyaluronidase activity was found to be related significa ntly to the fertilization rate. Moreover, we were able to establish va lues of hyaluronidase below which no fertilization occurred and above which fertilization of at least one oocyte was achieved. Conclusion: T hese results suggest that measurement of hyaluronidase activity may pr ovide a useful method for assessing the integrity of the acrosomal enz yme system, providing a simple and reliable predictor of the fertilizi ng potential of human sperm.