One of the findings from this study is that follistatin affects bovine embryo development. Follistatin is an acti-vin-binding protein, and it has antagonizing effects on the actions of activin in pituitary and granulosa cells. Recently, Silva and Knight reported that fol-listatin opposed the stimulatory effect of activin A on blastocyst yield when both activin A and follistatin were added to the medium during IVM of bovine COC. The results from the present study also show that follistatin neutralized the development-enhancing effect of activin A when both cytokines were added to medium during in vitro development at a concentration of 10 ng/m. Moreover, follistatin had a dose-dependent inhibitory effect on the development to morulae and blastocysts whether activin A was added or not. antibiotics levaquin
There is a possibility that follistatin antagonizes the action of endogenous activin A produced by embryo itself. In mice, it has been reported that activin A is present in all cells of the embryos, from the 1-cell stage to the compacted morula stage. Since transcripts of only the inhibin (3A subunit, and not transcripts of the a and (3B subunits, were detectable in bovine embryos from the 1-cell stage to morulae, at least the cleavage-stage embryos may produce activin A in cattle.