Figure 2From: Zona pellucida from fertilised human oocytes induces a voltage-dependent calcium influx and the acrosome reaction in spermatozoa, but cannot be penetrated by spermSperm binding test using unfertilised and fertilised human oocytes. Unfertilised human oocytes recovered after IVF failure (A) and fertilised oocytes with a high fragmentation rate two days after fertilisation (B), were cleared of bound spermatozoa and re-inseminated. After three hours, oocytes were similarly washed by repeated aspiration in a pipette, and the number of spermatozoa bound to the surface was determined under a microscope. Original magnification ×400.Back to article page