Bioscientifica Proceedings

Inhibition of luteolysis and establishment of pregnancy in pigs results from oestrogen secretion by the conceptuses and requires progesterone produced by the corpus luteum (CL). An integral part of maternal recognition of pregnancy in the pig is the redirection of prostaglandin (PG) F_2α,secretion from endocrine (blood) to exocrine (uterus) direction and an increase of PGE₂ synthesis in both the endometrium and conceptus. Uterine and conceptus PGE₂ synthases play an integrated role in establishing the PGE₂:PGF_2α ratio necessary for luteal maintenance. The luteolytic or luteotrophic changes in the CL are synchronised with the release of maternal pituitary and ovarian hormones. The presence of uterine oxytocin (OT) and luteinising hormone (LH) receptors are important for the luteolytic effect of PGF_2α. Conceptus oestrogen secretion coincides with autocrine and paracrine dialogue between the multiple conceptuses and uterine biological compounds and their receptors in trophoblast and endometrium.

© 2005 Society for Reproduction and Fertility