A baboon model for simulating pregnancy.

Estrogen and progesterone secreted by the corpus luteum regulate the function of the uterine endometrium in preparation for pregnancy. Embryonic signals superimposed on this steroid hormone-primed uterus further modulate the uterine environment to make it conducive to pregnancy. Understanding the signaling mechanisms that initiate the embryonic-maternal dialog in humans is not feasible. In an effort to elucidate the role of chorionic gonadotropin as a mediator of endometrial function in addition to its luteotrophic role, we have developed a simulated pregnant model in the baboon. Infusion of chorionic gonadotropin in a manner that mimics blastocyst transit induces major changes in the morphology and secretory activity of the endometrium. This model provides a method by which the function of various embryonic factors on endometrial can be tested in an in vivo model.