The Role of Progesterone in Implantation in the Sheep

Abstract

Merino ewes were ovariectomized on days 4, 8, or 12 of pregnancy and injected daily from that time with 1, 4, or 16 mg progesterone in oil. The ewes were killed on day 20 and examined for embryos. There was a clear effect of dose of progesterone on the number and viability of embryos. Of the ewes receiving 1, 4, and 16 mg progesterone there were 0 out of 12, 2 out of 11, and 11 out of 14 with viable embryos on day 20. The effect of increasing progesterone was also seen in significantly increased glandular and luminal epithelial cell heights in ewes receiving 16 mg per day.