Expression of inhibin/activin subunits and their receptors and binding proteins in human preimplantation embryos

Purpose: Our purpose was to study the role of inhibin/activin during embryo genesis. Methods: Transcripts of inhibin/activin subunits(alpha, beta(A), beta(B)), activin receptors (types I and II), and follistatin were detected by a reve rse transcriptase-polymerase chain reaction in human reproductive cells and preembryos cultured alone or co-cultured with human endometrial cells. Results: Transcripts of alpha, beta(A), beta(B) subunits were all detected in granulosa luteal cells, but only beta(A) units were detected in endometr ial stromal and decidualized cells. In human preimplantation embryos, none of these subunits were detected in embryos from the four-cell to the morula stage and only beta(A) subunits were detectable in blastocyst embryos. Act ivin receptors were detectable in all of the studied embryos and cells. Tra nscripts of beta(A), activin receptors, and follistatin were differentially expressed in human preimplantation embryos cultured in vitro and their exp ressions were significantly enhanced with the presence of endometrial strom al cells. Conclusions: Our data suggest that there is a possible endometrium-embryo i nteraction via endometrial activins and preimplantation embryo receptors an d that the embryonic expressions of these activins, their receptors, and bi nding proteins are dependent on embryonic stage.