Effect of Varying Doses of Progesterone on Implantation in the Ovariectomized Hamster.

Abstract

No delay in implantation was obtained in hamsters castrated on the second day of pregnancy and given daily doses of progesterone (2-.25 mg). Percentage of implantation obtained decreases as the dose level is lowered to .125 mg daily. At .0625 mg nidation may occur, but, in the majority of cases it either fails or resorption subsequently occurs. Nidation does not take place when .0312 mg is given.