Immunolocalization of ERβ and ERα in the late trophoblast culture (68 h). [A] Isolated CT cells are unstained (arrowhead) but strong ERβ nuclear and cytoplasmic immunostaining accompanies young ST aggregates (y). [B] CT cell associated with ST shows ERβ immunoreactivity (arrowhead). [C] Mature ST (m) shows a diminution of ERβ nuclear staining (solid > white arrows) with persisting cytoplasmic immunoreactivity. [D] Secondary antibody control. [E] Isolated CT cells show strong ERα immunostaining (arrowhead) persisting in young ST aggregates [y, E and F] but diminishing in mature ST [m; F and G]. [H] Secondary antibody control.