CONTROL OF PLACENTAL ENDOCRINE FUNCTION - ROLE OF ENZYME ACTIVATION IN THE ONSET OF LABOR

The high levels of cortisol present in the fetal circulation during the last week of gestation in certain domestic animals appear to initiate labour by increasing placental production of oestrogens. This endocrine change may be brought about by the activation or induction of placental C21-steroid 17α-hy-droxylase and C-17, 20 lyase. We review the evidence for this mechanism in the sheep and assess whether it could occur in other species. © 1979.