BETA-TRANSFORMING-GROWTH-FACTORS (TGF-BETA) AT THE PORCINE CONCEPTUS-MATERNAL INTERFACE - PART II - UTERINE TGF-BETA BIOACTIVITY AND EXPRESSION OF IMMUNOREACTIVE TGF-BETA (TGF-BETA-1, TGF-BETA-2, AND TGF-BETA-3) AND THEIR RECEPTORS (TYPE-I AND TYPE-II)

Porcine uterine tissues were collected from Days 10 to 14 of gestation (peri-implantation period) or corresponding days of the estrous cycle . Results indicated a marked increase in beta transforming growth fact ors (TGF beta 1, TGF beta 2, and TGF beta 3) and TGF beta receptor (ty pe I and type II) immunostaining in uterine luminal epithelium (ULE) b etween Days 10 and 14 of gestation, but there was no increase in ULE i mmunostaining on the corresponding days of the estrous cycle. Uterine glands and stroma were intensely immunopositive in pregnant gilts for TGF beta isoforms and their receptors, but immunostaining was weak to undetectable in cycling gilts. No differences were detected in myometr ium, in which immunostaining was moderate in both cycling and pregnant gilts. Additionally, TGF beta 2 and TGF beta receptor (type I and typ e II) immunostaining was detected in uterine monocyte/macrophage-like cells. Western blotting detected the presence of all three TGF beta is oforms in uterine luminal flushings. The CCL64 cell TGF beta bioassay detected bioactive TGF beta s in uterine luminal flushings on Days 12, 13, and 14 of gestation. These results strongly indicate that uterine expression of TGF beta s and their receptors is pregnancy specific an d that bioactive TGF beta s are present at the conceptus-maternal inte rface in the peri-implantation period in pigs. Thus TGF beta s are lik ely to be involved in autocrine-paracrine interactions between the mat ernal uterus and the conceptus.