title: The potential of early human embryos to form blastocysts, hatch from their zona and secrete HCG in culture.
abstract: Early embryos assessed to be unsuitable for transfer to patients or for cryopreservation were cultured either in minimum essential medium (MEM) or in synthetic human tubal fluid (HFT). A significantly higher percentage of embryos developed to blastocysts in MEM (26.5%) than in HTF (14.5%). Serum was not required for blastocyst formation nor for hatching in MEM. HTF containing 1% human cord serum failed to support blastocyst hatching. Haploid (monopronucleate) and diploid (bipronucleate) embryos formed blastocysts and hatched with a similar frequency but triploid (tripronucleate) embryos developed poorly. Human chorionic gonadotrophin (HCG) released by hatched and intrazonal blastocysts was detected between days 7 and 8 after fertilization. The mean total HCG produced by hatched blastocysts by day 14 was 19,500 mIU, but embryos trapped inside their zonae released a mean level of 1550 mIU. Serum was shown to stimulate the output of HCG from both hatched and intrazonal blastocyst tissues. Free beta- and alpha-subunits of HCG were not released by developing blastocysts, but low levels of beta-HCG were produced by some embryonic tissues between days 12 and 14 when degenerative changes were observed.
authors.affiliation: Department of Obstetrics and Gynaecology, University of Melbourne, Australia.
authors.forename: A
authors.initials: A
authors.lastname: Lopata
authors.forename: D L
authors.initials: DL
authors.lastname: Hay
mesh_terms: D001755:Blastocyst / Q000502:physiology*; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000502:physiology*; D005314:Embryonic and Fetal Development; D006801:Humans; D010063:Ovum / Q000502:physiology*; D015044:Zona Pellucida / Q000502:physiology*
chemical_list: D006063:Chorionic Gonadotropin