Blastocyst Survival in the Ovariectomized or Adrenalectomized—Ovariectomized Rat

The length of time blastocysts remained viable in the uterine lumen after ovariectomy or adrenalectomy and ovariectomy in the absence of exogenous hormone treatment was studied. Mated rats were ovariectomized or adrenalectomized—ovariectomized on Day 2 of pregnancy. The rats were killed at various intervals after operation, and the uteri were flushed to recover the blastocysts. Unimplanted blastocysts were recovered from both types of treated rats up to Day 14. The viability of these blastocysts was demonstrated by the induction of implantation after treatment with esterone and progesterone. It was concluded that (a) the adrenal glands are not involved in blastocyst survival in the ovariectomized rat, and (b) progesterone is not required for the maintenance of blastocyst viability for at least the first week in the uterus.