Recent advances in male factor infertility and intracytoplasmic sperm injection

Abstract

The first trial of recovering a preimplantation stage embryo from flushing of a rabbit oviduct and transferring the embryo to a foster mother was demonstrated by Walter Heape in 1890 (1). However, Chang et al (2) in 1959 reported the first successful fertilization of rabbit eggs in vitro. The first successful human pregnancy and birth after in vitro fertilization (IVF) was reported by Steptoe and Edwards in 1978 (3). IVF by insemination has been used to treat couples with male factor infertility for over a decade with relatively disappointing results, presumably because the sperm cells were unable to penetrate the zona pellucida and fuse with the oolemma. This has led to the application of gamete micromanipulation. The initial approach to assisted fertilization was to partially bypass the zona pellucida. An animal model developed by Gordon and Talansky (4) demonstrated that an artificial opening introduced in the zona pellucida before insemination enhanced fertilization. Partial zona dissection (PZD) involved mechanical opening of the zona pellucida by a narrow microneedle while the oocyte was suspended in a hyperosmatic solution. Unfortunately this technique has not been successful. Fertilization rates were very low and there was a relatively high incidence of polyspermy (the penetration of more than one spermatozoan).