Fig. 2. Chromatin decondensation at Hoxb during early embryogenesis. (A) FISH of Hoxb1 (red) and Hoxb9 (green) on nuclei from extra embryonic mesoderm (EEM) and primitive streak/adjacent mesoderm (PSM) of one E7.5 embryo. Nuclei were counterstained with DAPI (blue). Scale bar: 2 µm. (B) Distribution of squared interphase distances (d²) in µm² measured between probes for Hoxb1 and Hoxb9, on nuclei from EEM and PSM of one E7.5 embryo, and in ES cells differentiated with RA for 2 days.