No abstract

Trophoblastin, an antiluteolytic component from the embryo, was identified in the ewe by the means of intrauterine injections of homogenates from trophoblasts at 14--16 days pregnancy. Homogenates from embryos and their membranes at 21--23 days pregnancy did not extend the life of the corpus luteum, suggesting that trophoblastin synthesis occurs for only a short period. The trophoblastin was thermolabile (80 degrees C for 30 min) and inactivated by pronase. Treatment of ewes with oCS, hCG, and extracts of 120-day placentae did not affect the time of luteolysis. The protein appears to be insoluble at pH 7 or 8, but to dissolve readily at pH 9.6. After injection of homogenates or extracts from 15--16-day-old trophoblasts, the initial CL were maintained for more than 1 month in most cyclic recipient ewes. Surgical removal of embryos at 21--23 days resulted in luteal maintenace for more than 1 month in over 50% of the operated animals. All the maintained CL were secretory although their average weight was about one-half of that CL of normal pregnancy, suggesting the existence of complementary luteotrophic placental factors. The uteri of most of these pseudopregnant ewes were distended with a clear, sterile fluid.

No abstract

A glycoprotein coat was demonstrated on the outer surface of both the uterine and trophoblastic cells using ruthenium red, cationized ferritin, concanavalin A-peroxidase and phosphotungstic acid in HCl. No changes were observed on the uterine epithelial surface of cyclic or pregnant animals before or during blastocyst attachment (Day 15). However, the cytochemical reactions were different on the trophoblastic cells of blastocysts at Days 13 and 15, the ruthenium red and cationized ferritin sites of reaction and the concanavalin A receptors being more homogeneously distributed on the outer surface of Day-15 trophoblast. The phosphotungstic acid staining demonstrated a glycoprotein substance between the trophoblast and the uterine epithelium in adhesion areas by Day 18. The results suggest that biochemical changes occur in the composition or distribution of the trophoblastic cell coat during the process of blastocyst attachment in the ewe.

No abstract