EXPRESSION OF ACTIVINS AND TGF-BETA-1 AND BETA-2 RNAS IN EARLY POSTIMPLANTATION MOUSE EMBRYOS AND UTERINE DECIDUA

The expression of the mesoderm inducing factors, activins and TGF-beta -s, was characterized in 5 1/2-9 1/2 day mouse embryos and implantatio n sites by in situ hybridization. Activin beta(A) RNA was not detected within the embryo, but is expressed in nearby decidual cells from 5 t o 7 days. Thus activin A could play a role within the embryo during ga strulation. Activin beta(A) is also expressed in more mesometrially lo cated decidual cells from 6 to 9 1/2 days. Activin beta(B) and inhibin alpha RNAs were not detected, while a control tissue was highly posit ive. TGF-beta-1 is expressed in the secondary decidual zone and in dev eloping endothelial cells in the decidua and embryo. TGF-beta-2 is exp ressed in the mesometrial decidua at 6 1/2 days and in the midline of the cranial neural plate.