Steroids in pregnancy and parturition in the marsupial, Macropus eugenii

Abstract

Pregnancy in the tammar wallaby, Macropus eugenii may be prolonged by a long period of embryonic diapause of the 100-cell blastocyst; resumption of development occurs after removal of the suckling pouch young (RPY) or by exogenous progesterone injection. The corpus luteum is essential for the first 8 days of pregnancy, but is not required for normal development after this time. Normal parturition will only occur, however, if the corpus luteum is present up to at least day 21 of pregnancy. The corpus luteum produces and contains progesterone, but peripheral plasma values are low (1 ng/ml). The peak progesterone content in the corpus luteum is attained at day 23 RPY, and is followed by a peak ..