title: Evidence of sperm entry into assumed unfertilized human oocytes after sub-zonal sperm microinjection.
abstract: Sub-zonal sperm microinjection (SUZI) as a treatment for male factor infertility can facilitate fertilization, however, in many cases oocytes remain unfertilized even though the sperm is placed in close contact with the oolemma. In order to improve our understanding of gamete interaction in cases of failed fertilization, we have analysed the failed fertilized oocytes from both SUZI and conventional in-vitro fertilization. The fluorochrome Hoechst 33342 (which binds specifically to DNA) was used to check for the possible presence of paternal chromatin in the unfertilized oocytes. A significantly higher (P < 0.01) number of microinjected oocytes showed signs of fertilization 2-3 days after sperm microinjection compared to normally inseminated oocytes, 30/175 (17.1%) and 2/79 (2.5%) respectively. In addition, four out of eight couples returning for a second treatment by SUZI displayed anomalies in fertilization in both cycles. The semen characteristics of patients with or without anomalies in fertilization was not different. The irregularities observed in the fertilization process infer that certain male factor patients have intrinsic sperm anomalies lying at the sperm membrane and/or chromatin level that could lead to anomalies in the appearance of the pronuclei.
authors.affiliation: Clinique de Stérilité et d'Endocrinologie Gynécologique, Hôpital Cantonal Universitaire de Genève, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Urner
authors.forename: P G
authors.initials: PG
authors.lastname: Bianchi
authors.forename: A
authors.initials: A
authors.lastname: Campana
authors.forename: D
authors.initials: D
authors.lastname: Sakkas
mesh_terms: D000328:Adult; D002467:Cell Nucleus; D002843:Chromatin / Q000378:metabolism; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D008297:Male; D008845:Microinjections; D008846:Micromanipulation; D009865:Oocytes / Q000166:cytology*; D012016:Reference Values; D013084:Sperm-Ovum Interactions / Q000502:physiology*; D015044:Zona Pellucida
chemical_list: D002843:Chromatin