Presence of Egg Antigen in Immature Oocytes and Preimplantation Embryos

Abstract

THE availability of a species-specific antibody against mouse eggs which did not react with mouse somatic cells^1,2 has made it possible to determine the presence of the “egg antigen” in both oocytes and developing embryos. Oocytes were obtained from Swiss albino 1CR mice either by disruption of intact ovaries with thin needles (4 to 6-day-old mice) or by disruption of follicles (older mice). Unfertilized eggs were obtained from superovulated Swiss mice as before³. Embryos at different stages of development were flushed from oviducts and uteri of untreated Swiss mice at various times after mating. The day on which the vaginal plug became visible was counted as the first day of pregnancy. Postimplantation embryos were dissected by Kirby's⁴ technique and cumuli oophori and zonae pellucidae were removed by the standard procedure³. Trophoblast cultures were established from late blastocysts maintained in the wells of microtest tissue culture plates for 48 h in Eagle's minimum essential medium supplemented with 10% foetal bovine serum. Trophoblast giant cells were obtained from ectoplacental cones of 7.5-day-old embryos which had been treated for 15 min with a 0.25% trypsin solution, containing 200 µg of DNAase/ml. to remove adhering fibrinoid deposits⁵.