title: Zona-free oocyte fertilized with intracytoplasmic sperm injection and underwent further division: case report and literature review.
abstract: The zona pellucida (ZP) plays a protective role during fertilization and early embryonic development. It is related to sperm binding, the acrosome reaction, prevention of polyspermic fertilization, and holding blastomeres together before the morular stage. Zona-free oocytes are accidentally encountered. If these oocytes are healthy, they can be fertilized normally by intracytoplasmic sperm injection (ICSI). We reported on a couple with male infertility undergoing oocyte retrieval after ovarian hyperstimulation. Before the ICSI procedure, cumulus cells surrounding the oocytes were removed, which resulted in one oocyte escaping from its ZP. The zona-free oocyte was fertilized normally with ICSI and developed to the 8-cell stage. We observed that the zona-free zygote had the ability to further divide, despite its loose contact. The zona-free embryo was transferred with other zona-intact embryos, but the implantation failed. We conclude that zona-free oocytes can be rescued, fertilized with ICSI, and cultured for further transfer or cryopreservation.
authors.affiliation: Department of Obstetrics and Gynecology, China Medical College Hospital, 2, Yuh-Der Road, Taichung, Taiwan, R.O.C. d3531@hpd.cmcg.org.tw
authors.forename: Y Y
authors.initials: YY
authors.lastname: Hsieh
authors.forename: C C
authors.initials: CC
authors.lastname: Chang
authors.forename: H D
authors.initials: HD
authors.lastname: Tsai
mesh_terms: D000328:Adult; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D008297:Male; D020554:Sperm Injections, Intracytoplasmic; D015044:Zona Pellucida / Q000502:physiology*