THE INFLUENCE OF SPERM ZONA PELLUCIDA COLLISION RATES ON ZONA BINDING/

The satisfying success rates reported with intra-cytoplasmic sperm inj ection (ICSI) ureed clinicians and scientists to re-address the emphas is in the management of the male factor patient towards gamete manipul ation in order to circumvent the underlying problem causing fertilizat ion failure. We have designed a study to (i) calculate the collision r ate of a sperm population with the human zona pellucida, using a mathe matical hypothesis and (ii) use the calculated collision rate to evalu ate subsequent zona binding results obtained under hemizona assay cond itions. Microdroplets were used to co-incubate sperm and human oocytes in order to evaluate zona binding. Using microvolumes, the track foll owed by sperm, as well as the maximum distance travelled were employed to calculate the collision rate of sperm and zona pellucida. The sper m concentrations of swim up samples were adjusted to 4 x 10(6) and 0.8 x10(6) sperm ml(-1). Five separate droplets each of 20 mu l containin g 4 x 10(6) sperm ml(-1) (80000 motile sperm) and 200 mu l containing 0.8 x 10(6) sperm ml(-1) (160000 motile sperm), respectively, were pre pared. Both volumes were incubated for 18 h at 37 degrees C. The mean (+/-SD) number of spermatozoa tightly bound to hemizona, incubated in 20 mu l and 200 mu l sperm droplets, was 2444+/-612 and 548+/-315, res pectively (P=0.0001). The results can be used as a guideline to calcul ate the optimum insemination concentration needed for a specific sperm population to ensure the maximum collision rates with the oocyte.