Immunohistological localization of antigens related to human chorionic gonadotrophin and human placental lactogen in the uterus of pregnant beagle dogs.

A cross-reaction of anti-HCG and anti-HPL sera with related tissue antigens in normal beagle dog pregnant uteri, from thirty days of pregnancy to term, is reported. Using the immunoglobulin-peroxidase bridge technique, specific staining is localized in the glands of the spongy layer and in the deep uterine glands, but it is absent from the trophoblasts of the placental labyrinth. A specific reaction product is also observed in the surface and glandular epithelium of the chorion laeve. These findings suggest that certain antigens, which share antigenic determinants with HCG and HPL, are produced in the endometrial epithelium and not in the trophoblastic villi of pregnant beagle dogs.