THE SITE OF PRODUCTION OF OESTROGENIC HORMONES IN HUMAN PREGNANCY. II.

Abstract

ABSTRACT Spayed female mice were injected with human foetal adrenal and placental tissue from foetuses delivered by hysterotomy in cases of legal abortions. Vaginal smears were inspected daily for signs of oestrogenic activity. Oestrous smears were never encountered when either adrenal or placental tissue was injected, but when both tissues were injected together, the mice most often went into oestrus. From these results it is assumed that the oestrogens of human pregnancy are produced neither by the placenta nor by the foetal adrenal alone, but by a complex procedure involving both tissues. It is thought most likely that the foetal adrenals produce a steroid precursor which is metabolized into oestrogens by the placenta and excreted as such in the urine of the mother. Attempts to identify this precursor have so far failed.