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 embryogenesis. Methods: Transcripts of inhibin/activin subunits(alpha, beta(A), beta(B)), activin receptors (types I and II), and follistatin were detected by a reverse 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 endometrial 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. Activin receptors were detectable in all of the studied embryos and cells. Transcripts of beta(A), activin receptors, and follistatin were differentially expressed in human preimplantation embryos cultured in vitro and their expressions were significantly enhanced with the presence of endometrial stromal cells. Conclusions: Our data suggest that there is a possible endometrium-embryo interaction via endometrial activins and preimplantation embryo receptors and that the embryonic expressions of these activins, their receptors, and binding proteins are dependent on embryonic stage.