Comparative expression of TGF-alpha and EGF genes in the ovine conceptus and uterine endometrium in the peri-implantation period.

Control of growth and differentiation during mammalian embryogenesis may be regulated by growth factors. With the use of a very sensitive method, the reverse transcription-polymerase chain reaction, expression of some growth factor transcripts was examined during ovine peri-implantation development. Transcripts for transforming growth factor-alpha (TGF-alpha) were found in day 15 to day 30 conceptuses, and in uterine tissues. Epidermal growth factor (EGF) was not detectable in any ovine stages or tissues studied. TGF-alpha could be the normal physiological ligand for the epidermal growth factor receptor present on the trophoblastic tissues, and its expression pattern suggests an autocrine and paracrine role in the growth and differentiation of ovine embryos.