Expression of Inhibin/Activin Subunits and Their Receptors and Binding Proteins in Human Preimplantation Embryos

Abstract

Purpose: Our purpose was to study the role of inhibin/activin during embryogenesis. Methods: Transcripts of inhibin/activin subunits (α, β _A , β _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 α, β _A , β _B subunits were all detected in granulosa luteal cells, but only β _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 β _A subunits were detectable in blastocyst embryos. Activin receptors were detectable in all of the studied embryos and cells. Transcripts of β _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.