Expression of oncofetal fibronectin in porcine conceptuses and uterus throughout gestation.

Oncofetal fibronectin is reportedly expressed specifically by trophoblast tissue and some tumours and speculated to mediate placental attachment. In the present study, a monoclonal antibody (FDC-6) to human oncofetal fibronectin was used to characterize temporal and spatial changes in the expression of oncofetal fibronectin at the fetal-maternal interface of pigs. Conceptus and uterine tissues were collected from gilts throughout normal pregnancy and processed for immunohistochemical characterization. Results indicated that oncofetal fibronectin was constitutively expressed by both porcine conceptus and uterus throughout gestation. The most abundant staining for oncofetal fibronectin was found in the allantochorion and detectable levels of oncofetal fibronectin were also detected in luminal and glandular epithelial cells in the uterus. During the second-half of pregnancy, oncofetal fibronectin was also detected in fibroblast-like cells in the uterine stroma, but not in the stroma of the allantochorion. Owing to the non-invasive nature of the porcine placenta, the abundant expression of oncofetal fibronectin by the trophoblast and uterus may influence attachment between chorion and endometrium during pregnancy. Since attachment is the first step in implantation and placentation in all mammalian species, the pig may represent an excellent animal model to study interactions between trophoblast and endometrium mediated by oncofetal fibronectin.