estrogens from the blastocyst may exert their luteostatic effect on the uterus by causing prostaglandin f2 alpha , the presumed porcine uterine luteolysin , to be secreted in an exocrine ( toward the uterine lumen ) rather than an endocrine ( toward the endometrial stroma and vasculature ) direction during pregnancy .
C0014939
estrogens
C0032961
pregnancy