FIG. 4.

Proliferative defects in CycF^−/− placentas. (A) mRNA in situ hybridization on wild-type E9.5 embryos and placentas showing expression of cyclin F (left) and p21(right). Signal appears as red, while nuclei are blue. (B and C) Wild-type and CycF^−/− placentas at ×10 magnification. (D and E) Magnification of ×40 illustrates that BrdU-positive cells (brown) of the chorionic trophoblast layer make up roughly 25% of the cells in panel D, compared to around 13% of those in panel E. Sections in panels D and E were counterstained with hematoxylin to produce otherwise blue nuclei. Abbreviations: A, allantois; L, labyrinthine layer; S, spongiotrophoblast layer; G, giant cell layer; D, decidual layer.