Implantation and maintenance of pregnancy in mated rhesus monkeys following bilateral oophorectomy or luteectomy with and without progesterone replacement.

Six mated rhesus monkeys were bilaterally oophorectomized between the fourth and sixth day after ovulation, and received silastic implants containing crystalline progesterone subcutaneously. Five mated monkeys were subjected to luteectomy 5 or 6 days after ovulation. Three of these received progesterone implants subcutaneously. Pregnancy occurred in one oophorectomised monkey and in all three luteectomised monkeys treated with progesterone. It was evident from the steroid patterns observed in the pregnant monkeys that the ovarian tissue other than the corpus luteum contributes to part of the oestrogen seen around the time of implantation. The corpus luteum apears to be the main source of progesterone in the peripheral plasma during this period. Placental progesterone production in early pregnant rhesus monkeys starts at three weeks after ovulation and the placental production of progesterone precedes that of oestrogen.