This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Webley, G. E. Articles by Hearn, J. P. Search for Related Content PubMed Articles by Webley, G. E. Articles by Hearn, J. P.

Stimulation of immunoreactive inhibin production by preimplantation embryos during early pregnancy in the marmoset monkey (Callithrix jacchus)

Summary. The role of the embryo in promoting increased plasma concentrations of immunoreactive inhibin after conception in the marmoset monkey was determined by flushing embryos from the uterus between days 5 and 9 after ovulation (implantation commences on days 11–12). Blood samples were taken from each animal (three times a week) after ovulation until the end of the luteal phase. Plasma inhibin concentrations were measured using a radioimmunoassay based on antisera against a synthetic fragment of the -subunit of human inhibin. When embryos were flushed on days 5 and 6 (n = 6) after ovulation inhibin concentrations did not exceed 250 ng ml^–1 for the duration of the luteal phase. In contrast when embryos were flushed on days 7 (n = 4), 8 (n = 4) and 9 (n = 3) maximum concentrations of inhibin always exceeded 250 ng ml^–1, reaching > 400 ng ml^–1 when embryos were flushed on days 8 and 9. Inhibin concentrations remained high for the duration of the luteal phase, which varied in length between 20 and 32 days. Significantly (P < 0·01) higher mean plasma concentrations of immunoreactive inhibin were first recorded on days 7–8 after ovulation in animals that had embryos flushed on days 7, 8 and 9 compared with concentrations in animals that had embryos flushed on days 5 and 6. Inhibin could not be detected in the medium of embryos cultured for up to 2 weeks. In two control animals, inhibin concentrations exceeded 250 ng ml^–1 after sham operation on day 6, whereas inhibin did not exceed 250 ng ml^–1 when unfertilized eggs were flushed from the uterus of an animal on day 8 after ovulation. Progesterone concentrations did not differ significantly among animals irrespective of the day of embryo flushing. The results suggest that the marmoset pre-implantation embryo provides a signal on days 7–8 which triggers an increase in luteal inhibin production. The continued presence of this putative signal was not necessary for maintaining increased inhibin production.

Keywords: embryo; inhibin; pregnancy; marmoset monkey