A preclinical evaluation of pronuclear formation by microinjection of human spermatozoa into human oocytes.

In vitro fertilization (IVF) is recognized as an accepted treatment for male infertility. However, the fertilization rate is significantly lower than the fertilization rate of other IVF patient groups. Some male factor infertility patients still have a basic semen quality too poor for treatment by IVF. Microinjection of a spermatozoon directly into ooplasm has been recommended to assist fertilization in this subfertile population. This study found that oocytes from 5 of 11 patients microinjected with human spermatozoa demonstrated successful pronuclear formation and correlated with the incidence of pregnancy in these patients transferred with same-source oocytes inseminated by standard protocols. This initial evidence promotes the supposition of clinical feasibility of assisted fertilization by sperm microinjection.