IMPLANTATION IN ARMADILLOS OVARIECTOMIZED DURING THE PERIOD OF DELAYED IMPLANTATION

Abstract

SUMMARY The effect of ovariectomy during delayed implantation on the fate of the free blastocyst has been studied in the armadillo. If bilateral ovariectomy is performed about the middle of the 4-month delay period, implantation occurs 30–34 days later and is indistinguishable from normal implantation. In animals ovariectomized toward the end of the delay period, implantation occurs at the time when normal implantation would have been expected, which is less than 30 days postoperatively. However, resorption or abortion follows shortly thereafter. Removal of the corpus luteum towards the end of the delay period for the most part results in loss of the blastocyst and non-implantation. Removing the corpus luteum in early gestation causes loss of the embryos, but no effect was observed following loss of the corpus luteum in animals past approximately the first third of gestation. A possible explanation of the findings is discussed.