title: Effect of post-ovulatory age and calcium in the injection medium on the male pronucleus formation and metaphase entry following injection of human spermatozoa into golden hamster oocytes.
abstract: The occurrence of parthenogenetic activation is a major hurdle in obtaining sperm chromosome metaphases after heterospecific intracytoplasmic sperm injection (ICSI) of golden hamster oocytes with human spermatozoa. We addressed two potential contributors to parthenogenetic activation namely, post-ovulatory age of the oocyte and Ca2+ content of the injection medium. In serial experiments, hamster oocytes were retrieved at 11.5, 13, 16 and 21 h after the ovulatory dose of human chorionic gonadotrophin (HCG) and microinjected with human spermatozoa suspended alternately in a regular (1.9 mM Ca2+) or a Ca2+-free medium. A progressive decrease in the rates of male pronucleus (MPN) formation and metaphase entry and increase in the rates of parthenogenetic activation without male pronucleus occurred with increasing post-ovulatory age. The favourable influence of Ca2+-free injection medium on the mean rates of MPN and metaphase entry was restricted to the relatively older oocytes (MPN 16 h: 49.5 versus 32.3%, P< 0.008; 21 h: 22.2 versus 11.1%, P< 0.001; metaphase entry 16 h: 36.8 versus 25.1%, P< 0.02; 21 h: 13.3 versus 5.2%, P< 0.01 in the Ca2+-free and regular groups respectively). Our data confirm the increased activation sensitivity with post-ovulatory ageing and its adverse influence on the MPN formation and metaphase entry after heterospecific ICSI of hamster oocytes.
authors.affiliation: Infertility Centre, Department of Obstetrics and Gynaecology, University Hospital, Ghent, Belgium.
authors.forename: P T
authors.initials: PT
authors.lastname: Goud
authors.forename: A P
authors.initials: AP
authors.lastname: Goud
authors.forename: H
authors.initials: H
authors.lastname: Laverge
authors.forename: P
authors.initials: P
authors.lastname: De Sutter
authors.forename: M
authors.initials: M
authors.lastname: Dhont
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006224:Cricetinae; D003470:Culture Media; D005187:Fallopian Tubes / Q000502:physiology; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008647:Mesocricetus; D008677:Metaphase; D009865:Oocytes / Q000502:physiology*; D010060:Ovulation; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000166:cytology / Q000502:physiology*; D014960:X Chromosome / Q000235:genetics; D014998:Y Chromosome / Q000235:genetics
chemical_list: D003470:Culture Media; D002118:Calcium