Beta Transforming Growth Factors (TGFβ) at the Porcine Conceptus-Maternal Interface. Part I: Expression of TGFβ1, TGFβ2, and TGFβ3 Messenger Ribonucleic Acids1

Spatial and temporal mRNA expression of beta transforming growth factors (TGFbeta1, TGFbeta2, and TGFbeta3) in porcine uterus and conceptuses was determined during the peri-implantation period (Days 10-14 of gestation). Northern blotting identified a major 3. 5-kilobase (kb) and a minor 2.5-kb transcript for TGFbeta1 mRNA. TGFbeta2 transcripts were 6.2 kb, 5.4 kb, and 2.7 kb, and a single 3. 5-kb transcript was detected for TGFbeta3. With semiquantitative in situ hybridization analysis, progressive increases were detected in TGFbetas 1, 2, and 3 mRNA expression in uterine luminal epithelium (ULE), uterine glands (UGs), and underlying stroma (stroma spongiosum, SS) from Days 10 through 14 of gestation (p < 0.05). In myometrium, TGFbeta mRNA expression did not differ between Days 10 through 14 of gestation. In porcine conceptuses, TGFbetas 1, 2, and 3 mRNA expression was detected in trophectoderm, endoderm, embryonic ectoderm, and mesoderm. For the three TGFbeta isoforms examined, mRNA expression increased 2- to 4-fold in trophectoderm and endoderm between Days 10 and 14 of gestation. TGFbeta1 mRNA levels increase significantly in embryonic ectoderm, but not mesoderm, between Days 12 and 14 of gestation; during that same time, TGFbeta2 mRNA levels increased, but no change was detected in TGFbeta3 mRNA levels, in embryonic ectoderm and mesoderm. Progressive increases in TGFbeta mRNA expression in conceptus trophectoderm, endoderm, ULE, UGs, and SS suggest important roles for these growth factors in porcine conceptus development during the peri-implantation period.