Title: Effects of Hypophysectomy on Blastocyst Survival, Progesterone Secretion and Nidation in the Spotted Skunk
Abstract: 12 female skunks were hypophysectomized during the 7-month preimplantation period. Sham operations were performed on 7 skunks by drilling through the basisphenoid but without exposing the pituitary. 22 skunks remained as controls. Complete hypophysectomy significantly reduced peripheral plasma progesterone levels within 40 days while there was a tendency for values to increase in sham hypophysectomized skunks. The only obvious effect hypophysectomy had on ovarian histology during the preimplantation period was the abolition of all antral follicles; corpora lutea remained unchanged for up to 90 days. Blastocysts from hypophysectomized skunks were undergoing a slow attrition of cells after Day 34, and there was some indication that hypophysectomy may have a deleterious effect as early as Day 22. Hypophysectomy significantly prolonged the preimplantation period in 6 out of 7 skunks. It was concluded that the pituitary is essential for initiation of nidation.