Differential expression of beta transforming growth factors (TGFβ1, TGFβ2, and TGFβ3) and their receptors (type I and type II) in peri- implantation porcine conceptuses

Abstract

Beta transforming growth factors (TGFβ1, TGFβ2, and TGFβ3) and type I and II TGFβ receptors were immunohistochemically localized in peri- implantation porcine conceptuses (embryos and associated membranes) collected on Day 10 through Day 14 of gestation. Our results indicate specific immunolocalization of TGFβ isoforms and their receptors in conceptuses during these gestational days. In parietal endoderm, TGF 1/4 b1 immunoreactions were weak to undetectable, TGFβ2 immunoreactions were intense, and TGFβ3 immunoreactions were intermediate in intensity to TGFβ2 and TGFβ1. In contrast to immunoreactions in endoderm, TGFβ1 and TGFβ3 immunostaining in trophectoderm (Tr) was intense. Differences in TGFβ2 immunostaining of Tr were observed from Days 10 to 14 of gestation. A drastic decrease in cytoplasmic immunostaining of ectoderm and mesoderm was detected from Days 12 to 14 for all TGFβ isoforms and type II receptor; however, type I receptor immunoreactions were consistently detected between Days 10 and 14. Concurrent expression of both type I and type II receptors in the peri-implantation conceptuses suggests that porcine conceptuses are capable of binding and responding to TGFβs during this period. Differential expression of the three TGFβ isoforms suggests different roles for TGFβs 1, 2, and 3 in conceptus development. Our results suggest possible roles for TGFβs in early growth and differentiation of the embryo, differentiation of the Tr, and implantation.