Plasma progesterone level in the female armadillo during delayed implantation and gestation: preliminary report.

Ovulation in the armadillo was followed by an increase in the plasma level of progesterone to 10 ng/ml. The plasma concentration of progesterone decreased to approximatley 5 ng/ml during the 3 1/2 mo of delayed implantation and then increased to approximately 20 ng/ml for the 4 1/2 mo period of gestation.