Bioscientifica Proceedings

This review integrates established information with new insights into molecular and physiological mechanisms responsible for events leading to pregnancy recognition, endometrial receptivity, and implantation with emphasis on sheep. After formation of the corpus luteum, progesterone acts on the endometrium and stimulates blastocyst growth and elongation to form a filamentous conceptus (embryo/fetus and associated extraembryonic membranes). Recurrent early pregnancy loss in the ...

Early pregnancy is maintained in ruminants through the actions of conceptus-derived interferon (IFN)-tau on the endometrium. IFN-tau alters uterine release of PGF2α, which results in rescue of the corpus luteum and continued release of progesterone. The mechanism of action of IFN-tau includes inhibition of oestradiol receptors, consequent reduction in oxytocin receptors, activation of a cyclooxygenase inhibitor, and a shift in the PGs to favour PGE2 ...

Timing of conceptus growth and attachment to the uterine luminal epithelium is regulated by progesterone secretion from the corpus luteum and by expression of progesterone receptor in the uterine epithelia and stroma. Conceptus growth and uterine attachment are temporally associated with the disappearance of progesterone receptors from uterine epithelia. While the loss of progesterone receptor from the endometrial epithelia on day 10 of the oestrous cycle and pregnancy h...

This review highlights information on conceptus-uterus interactions in the pig with respect to uterine gene expression in response to estrogens and interferons (IF Ns) secreted from elongating conceptuses. Pig conceptuses release estrogens for pregnancy recognition, but also secrete IENs that do not appear to be antiluteolytic. Estrogens and IFNs induce expression of largely non-overlapping sets of genes, and evidence suggests that pig conceptuses orchestrate essential e...

Abstract unavailable© 2009 Society for Reproduction and Fertility...