DIFFERENTIAL EXPRESSION OF BETA-TRANSFORMING GROWTH-FACTORS (TGF-BETA-1, TGF-BETA-2, AND TGF-BETA-3) AND THEIR RECEPTORS (TYPE-I AND TYPE-II) IN PERIIMPLANTATION PORCINE CONCEPTUSES

Beta transforming growth factors (TCF beta 1, TGF beta 2, and TGF beta 3) and type I and II TGF beta receptors were immunohistochemically lo calized in peri-implantation porcine conceptuses (embryos and associat ed membranes) collected on Day 10 through Day 14 of gestation. Our res ults indicate specific immunolocalization of TGF beta isoforms and the ir receptors in conceptuses during these gestational days. In parietal endoderm, TGF beta 1 immunoreactions were weak to undetectable, TGF b eta 2 immunoreactions were intense, and TGF beta 3 immunoreactions wer e intermediate in intensity to TGF beta 2 and TGF beta 1. In contrast to immunoreactions in endoderm, TGF beta 1 and TGF beta 3 immunostaini ng in trophectoderm (Tr) was intense. Differences in TGF beta 2 immuno staining of Tr were observed from Days 10 to 14 of gestation. A drasti c decrease in cytoplasmic immunostaining of ectoderm and mesoderm was detected from Days 12 to 14 for all TGF beta isoforms and type II rece ptor; however, type I receptor immunoreactions were consistently detec ted between Days in and 14. Concurrent expression of both type I and t ype II receptors in the peri-implantation conceptuses suggests that po rcine conceptuses are capable of binding and responding to TGF beta s during this period. Differential expression of the three TGF beta isof orms suggests different roles for TCF beta s 1, 2, and 3 in conceptus development. Our results suggest possible roles for TCF beta s in earl y growth and differentiation of the embryo, differentiation of the Tr, and implantation.