Fertilization abnormalities following human in vitro fertilization and intracytoplasmic sperm injection.

Fertilization abnormalities are commonly encountered following in vitro fertilization. The widespread introduction of assisted fertilization methods has rapidly led to a changes in both the incidence and types of these aberrations. Such abnormalities can be identified by careful morphological evaluation at the early zygote stage, of pronuclei as well as of polar body formation, and may be confirmed by cytogenetic assessment. The recognition and understanding of fertilization abnormalities have led to the development of novel techniques aimed at preventing them, as well as recent bold attempts at correction. Removal of one pronucleus may allow some triploid embryos to revert to a normal diploid stage. These new developments should provide insight into the understanding of parthenogenesis, androgenesis, and gynogenesis in the human. Microsc. Res. Tech. 61:358-361, 2003. Copyright 2003 Wiley-Liss, Inc.