Embryo—Maternal Interactions after Diapause in a Marsupial

Abstract

In all mammals, development of the embryo depends on complex interactions with the uterus. In the most commonly used experimental animals, mice and rats, the development of the egg cylinder and the formation of the invasive placenta at implantation early in gestation complicate analysis, so that the signals passing between the uterus and mother in early pregnancy are not clearly defined. Marsupials, in contrast, remain free and unattached to the uterus for two thirds of gestation, surrounded by an acellular mucoid coat and keratinous shell that prevents direct cell—cell contact between the endometrium and trophoblast cells. Embryo development must therefore be controlled by soluble factors i..