Relationship between ovarian and placental steroid production during early pregnancy in the marmoset monkey (Callithrix jacchus)

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Abstract
Concentrations of progesterone, 17.alpha.-hydroxyprogesterone, estrone and estradiol-17.beta. in peripheral and utero-ovarian vein blood were measured during the first 60 days of pregnancy. The same hormones were also measured in peripheral blood samples from non-fertile cycles. Peripheral levels of 17.alpha.-hydroxyprogesterone, estrone and estradiol increased gradually during early pregnancy whereas concentrations of progesterone declined. The patterns of secretion of progesterone, 17.alpha.-hydroxyprogesterone and estrone, but not estradiol, were significantly different in fertile and non-fertile cycles by 15 days after ovulation. Comparison of hormone values in peripheral and utero-ovarian vein samples from ovaries with and without corpora lutea (Days 7, 9, 13, 21, 40 and 60 or pregnancy) showed that progesterone was secreted by the corpus luteum until at least Day 40 by which time there was also placental secretion. Although 17.alpha.-hydroxyprogesterone was secreted by the corpus luteum, the relative contribution of luteal and placental secretion after Day 21 was not clear. Estrone secretion by the corpus luteum was no longer detectable by Day 40, but placental estrone secretion appeared to be present by this time. The corpus luteum did not secrete significant amounts of estradiol at any stage of early pregnancy, although there was evidence for placental secretion by Day 40. Progesterone secretion by the corpus luteum of early pregnancy apparently continues beyond the time when estrogen secretion has declined. The corpus luteum to placental shift in the marmoset appears to occur at a later stage of pregnancy than it does in the macaque monkey and probably also in man.