ABSTRACT
Spermatozoa sometimes fail to fertilize even when they are artificially placed in close proximity of eggs during conventional in vitro fertilization (IVF). Fertilization failure in IVF is particularly common where there are grossly abnormal semen parameters or when the number of spermatozoa is insufficient. Gamete micromanipulation is the only way to overcome this problem in most cases. The different techniques developed in this regard focused initially on the obstacle to sperm penetration represented by the zona pellucida (ZP), by thinning it through exposure to enzymes or creating an opening through localized chemical digestion, mechanical breach, or even photoablation.1-3 The placing of the spermatozoon beneath the zona has yielded consistent results achieving a fertilization rate of ~20%.4 However, these techniques have been almost abandoned because of limiting factors such as the need for many functional spermatozoa with good progressive motility, and complications such as multiple sperm penetration.5
