Synthesis of progesterone by the placenta of a marsupial.

Abstract

Departments of Zoology and Obstetrics & Gynaecology, The University of Western Australia, Western Australia 6009, Australia, and † Department of Anatomy, University ofBristol, Bristol, BS8 1TD (Received 18 December 1974) Because of its minute size, simple yolk-sac (chorio-vitelline) organization and brief existence relative to the total period of development of the embryo, it has been suggested that the marsupial placenta has no endocrine function (Ryan, 1969; Sharman, 1970; Short, 1972; Shorey & Hughes, 1973). However, Heller (1973) has found that the sensitivity of the myometrium of the female quokka (Setonix brachyurus) is influenced by pregnancy and by administration of progesterone or stilboestrol. Therefore, it seemed worthwhile to investigate the possibility that the placenta of this marsupial may have the capacity to synthesize steroid hormones. Preliminary experiments were conducted to determine the ability of isolated placental tissue to convert pregnenolone to progesterone. Foetuses, together with their associated membranes, were removed from