title: Experimental demonstration that mammalian oocytes are not selective towards X- or Y-bearing sperm.
abstract: Mammalian oocytes are thought to be neutral as for X- or Y-bearing sperm selection is concerned, and penetration of an oocyte by an X- or a Y-bearing sperm is considered a random event. This assumption is mainly based on a posteriori evidences of a nearly equal sex ratio at birth, but it has never been experimentally demonstrated. We have designed a simple experiment, which allowed the penetration of an oocyte by more than one sperm and the further sexing by PCR of each single pronucleus present within the ooplasm. For the first time, we provide experimental evidence that mammalian oocytes do not play a selecting role since a single oocyte may be simultaneously fertilised by both X- and Y-bearing sperm.
authors.affiliation: Dipartimento di Medicina Sperimentale, Sezione di Istologia ed Embriologia, Parma, Italy. maurizio.zuccotti@unipr.it
authors.forename: Maurizio
authors.initials: M
authors.lastname: Zuccotti
authors.forename: Vittorio
authors.initials: V
authors.lastname: Sebastiano
authors.forename: Silvia
authors.initials: S
authors.lastname: Garagna
authors.forename: Carlo Alberto
authors.initials: CA
authors.lastname: Redi
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005260:Female; D005307:Fertilization in Vitro; D008297:Male; D051379:Mice; D009865:Oocytes / Q000166:cytology / Q000502:physiology*; D012744:Sex Ratio; D013084:Sperm-Ovum Interactions / Q000502:physiology*; D013094:Spermatozoa / Q000502:physiology*; D014960:X Chromosome / Q000502:physiology*; D014998:Y Chromosome / Q000502:physiology*