Abstract
It is evident that members of several growth factor families are actively involved in embryogenesis from its earliest phases. Several reports also indicate the oviduct as a possible source of growth factors, suggesting an active role of this organ in mammalian embryonic development. The aim of this study was to investigate the presence of activin/inhibin subunits in bovine oviduct since activin is a well‐characterised morphogen in amphibian development. The presence of transcripts for α. β~A~, and β~B~ subunits was investigated by analysing oviduct epithelial cells mRNA with reverse transcription‐polymerase chain reaction (RT‐PCR). Moreover, antisera specific for the three subunits were used for the Western blot analysis of the proteins secreted by oviduct epithelial cells in vitro and for their immunohistochemical localisation in different oviductal regions. Oviduct epithelial cells expressed only the β~A~‐subunit gene. Immunoreactive material was present among in vitro secreted proteins, indicating that the transcript is translated into a polypeptide that has been localised in the epithelium of both the ampullary and isthmic tract of the organ. Consistent with these results, the antisera for the α and β~B~ subunits did not recognise any specific antigen either among secreted proteins or in the sections. These results indicate that β~A~ subunit gene is expressed in bovine oviduct epithelial cells, and the protein is secreted in vitro and can be found along the whole extension of the organ. In the absence of α or β~B~ subunits, this suggests that activin A is present in bovine oviduct. Such a finding would be consistent with an embry‐otrophic activity of this organ, but definitive conclusions on the target tissue and the specific functions of oviductal activin require further studies. © 1995 Wiley‐Liss, Inc.