Fig. 4. Cdx2 levels are variable and initially without correlation to Oct4. (A) Cdx2 and Oct4 distribution within the same embryo at defined stages of development. For every embryo the counterstained DNA is shown in the row below. White and green arrowheads indicate nuclei of interest of inside and outside cells, respectively. Actin (red) marks the cell membranes. All images are single optical sections. Scale bar is 20 µm. (B) Scatter plots showing the normalized mean fluorescence intensity of Cdx2 relative to Oct4 for individual blastomeres. Each dot represents one blastomere; different colors represent different embryos. Red lines mark the background fluorescence level.