Expression of epidermal growth factor and transforming growth factor-alpha in fallopian tube epithelium and their role in embryogenesis.

We studied the expression of epidermal growth factor (EGF) and transforming growth factor (TGF)-alpha in human fallopian tube epithelium at various menstrual stages. Immunohistochemical staining using anti-EGF and anti-TGF-alpha antibodies showed a specific staining in ampullary tube epithelium at late follicular and luteal stages but the staining was very weak at the early follicular stage. Quantitative reverse transcription and polymerase chain reaction (RT-PCR) using beta-actin mRNA as an internal standard revealed the menstrual-stage-specific expression of EGF and TGF-alpha gene transcripts: amounts of EGF and TGF-alpha mRNA relative to those of beta-actin were significantly higher at late follicular and luteal stages than at the early follicular stage. To clarify the biological role of these growth factors, mouse 2-cell embryos were cocultured with human fallopian tube epithelial cells with or without blocking the action of these growth factors. Cocultures significantly promoted blastocyst formation, but this promotive effect of the tubal epithelial cells was completely abolished by the addition of anti-EGF and/or anti-TGF-alpha monoclonal neutralizing antibodies to the coculture system. These results demonstrated that EGF and TGF-alpha were synthesized and expressed in fallopian tube epithelium at specific menstrual stages, and may be involved in early embryonic development.