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 implantation sites by in situ hybridization. Activin beta(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 beta(A) is also expressed in more mesometrially located 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 positive. TGF-beta-1 is expressed in the secondary decidual zone and in developing endothelial cells in the decidua and embryo. TGF-beta-2 is expressed in the mesometrial decidua at 6 1/2 days and in the midline of the cranial neural plate.