Expression of activins and TGFβ1 and β2 RNAs in early postimplantation mouse embryos and uterine decidua

The expression of the mesoderm inducing factors, activins and TGF β s, was characterized in 5 1 2 − 9 1 2 day mouse embryos and implantation sites by in situ hybridization. Activin β A RNA was not detected within the embryo, but is expressed in nearby decidual cells from 5 to 7 days. Thus activin A could play a role within the embryo during gastrulation. Activin β A is also expressed in more mesometrially located decidual cells from 6 to 9 1 2 days. Activin β B and inhibin α RNAs were not detected, while a control tissue was highly positive. TGF β 1 is expressed in the secondary decidual zone and in developing endothelial cells in the decidua and embryo. TGF β 2 is expressed in the mesometrial decidua at 6 1 2 days and in the midline of the cranial neural plate.