Serum Placental Lactogen in Mice in Relation to Day of Gestation and Number of Conceptuses

Abstract

Placental lactogen (PL) was measured throughout gestation by radioreceptor assay. Serum mouse PL (mPL) levels were low at the beginning of gestation, peaked at day 10, and returned to low levels again by day 13. From day 13 until term, mPL levels remained low. No circadian rhythm in mPL levels was seen over 2 different 24-h periods. Mouse PL levels were correlated with the number of conceptuses in an animal from days 9 to 18 of gestation.