Fig. 2. The keratin cytoskeleton is collapsed in primary cultures of Mrj^-/- trophoblast cells. (A) Keratinfilament (red) organization in trophoblast giant cells derived from wild-type and Mrj^-/- chorionectoplacental cone explants. (B) Quantification of the types of keratin-filament organization observed in trophoblast giant cells derived from wild-type and Mrj^-/- chorionectoplacental cone explants. (C) Ultrastructure of a keratin aggregate (surrounded by broken line) in a Mrj^-/- trophoblast giant cell at E8.25. (D) Mrj expression (red) in trophoblast giant cells of a wild-type conceptus at E8.25. Right, higher-magnification of boxed region in the left panel. (E) Nuclear (left), cytoplasmic (center), and both nuclear and cytoplasmic (right) Mrj expression in wild-type trophoblast giant cells in vitro. Arrowheads indicate trophoblast giant cells with undetectable Mrj expression. Broken line indicates the periphery of a trophoblast giant cell. (A,D,E) DNA is blue. ch, chorion; em, embryo; pan-CK, pan-cytokeratin; TGC, trophoblast giant cells. Scale bars: 10 µm in A,E; 0.5 µm in C; 20 µm (left) and 10 µm (right) in D.