ABSTRACT
Spermatozoa sometimes fail to fertilize even when they are artifi cially placed in close proximity to 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 insuffi cient. 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 photo ablation (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 abandoned because of limiting factors such as the need for many functional spermatozoa with good progressive motility, and complications like multiple sperm penetration (5).
