The Control of Blastocyst Activity

摘要: It is perhaps fortuitous that the phenomenon of embryonic diapause exhibited by laboratory species such as rat and mouse since it has prvided us with an extremely effective tool for elucidating endometrial-blastocyst interactions leading to implantation. Much early work these concentrated on determining hormonal requirements implantation (Canivenc Laffargue 1956; McLaren 1970; Psychoyos 1973). was discovered administration progesterone animals ovariectomised in pregnancy resulted a state during which gestation indefinitely suspended at immediate preimplantation phase. The subsequent minute dose oestrogen, however, rapid precipitation response (Nalbandov 1971). way presence or absence oestrogen led stimulation inhibition been focus much current research endocrine control endometrial function. As consequence investigations, two hypotheses have advanced concerning role this hormone, (a) induces release embryotrophic secretions are either not synthesized released delay phase, (b) inactivation withdrawal blastocyst inhibitor manufactured progeste rone-dominated uterus diapause. evidence against each alternative but mutually exclusive presented following discussion.