The influence of a mineral oil overlay on the zona pellucida binding potential of human spermatozoa.

The objective of the study was to evaluate the effect of mineral oil on zona pellucida binding potential of human spermatozoa. The study compared zona binding using micro volume droplets under mineral oil as apposed to micro droplets in cryopreservation straws. Spermatozoa from eight proven fertile sperm donors were used. One hundred and fifty five matched hemizonae in 50 microliters, 100 microliters and 200 microliters insemination sperm droplets were co-incubated; (i) under mineral oil and (ii) 0.5 ml plastic cryopreservation straws. The results were analysed to determine the number of the zona bound spermatozoa during each experiment. Microvolumes with an oil overlay had a decrease in sperm bound per hemizona of 38% (mean +/- SD; 563 +/- 415 vs. 921 +/- 597), 51% (mean +/- SD; 392 +/- 359 vs. 800 +/- 566 sperm) and 18% (mean +/- SD; 502 +/- 369 vs. 618 +/- 445) in 200 microliters, 100 microliters and 50 microliters respectively, compared to microvolumes in cryopreservation straws. It was concluded that mineral oil may have some detrimental factors which interfere with zona binding of spermatozoa.