Estrogen contents in uterine and placental tissue during late pregnancy and at parturition of rats

Abstract

The estrogen levels in the blood, uterine and placental tissue of rats were determined during late pregnancy and at parturition.
The results obtained were as follows:
1. Estrogen levels in the blood during late pregnancy were increased rapidly from 15 to 17 days of pregnancy and the variation of values until 22 days of pregnancy was not significant. The remarkable increase occured at parturition.
2. Estrogen contents in the uterine tissue during late pregnancy and at parturition were lower than those of the placental tissue, the variation during experimental period was also not significant. The contents were decreased at parturition.
3. Estrogen contents in the pleacental tissue during late pregnancy were increased as pregnancy progsesses and a dramatic increase was observed at parturition.