Uterine histology and prostaglandin concentrations and utero-ovarian venous steroid and prostaglandin concentrations during the luteal phase of the menstrual cycle in baboons (Papio spp.) with or without an IUD.

Arachis oil was infused via the oviducts into the uterus of baboons 6-9 days after ovulation; uterine tissue was collected towards the end of the luteal phase (3-7 days after the oil infusion) for histological assessment of the occurrence of any deciduomal reaction. To exclude the possibility that a variation in the endogenous steroid concentrations was responsible for any observed variation in the incidence of the deciduomal reaction, blood samples were collected and assayed for progesterone and oestradiol-17 beta. The effect of the IUD on endometrial prostaglandin release was examined by measuring PGE and PGF concentrations in uterine tissue and utero-ovarian venous plasma. The IUD stimulated a deciduomal response in every animal, whereas the traumatization with arachis oil had no such effect; the variation in the peripheral and utero-ovarian steroid levels could not explain the variation in the incidence of the deciduomal reaction. Greater concentrations of PGF but not PGE were present in the endometria of those animals bearing an IUD and in which a deciduomal reaction had been stimulated. The corpus luteum was the major source of progesterone and of oestradiol-17 beta, although non-luteal ovarian tissue also secreted oestradiol-17 beta.