Figure 3-S2

(A, B) Transverse sections taken in the anterior PSM (A, 0–100 μm away from last somite boundary) or posterior PSM (B, 200–300 μm away from last somite boundary) on 12–14 s stage embryos co-stained for Fibronectin (FN, red) and F-actin (green). Asterisks denote PSM surface cells. Scale bars = 10 μm. (C) Quantification of PSM surface cell aspect ratio in the anterior and posterior portions of the PSM. Sample size: n = 93 cells (anterior PSM) and 92 cells (posterior PSM) from three embryos. Anterior vs posterior, p=7.46e-5. (D–E) Quantification of the mean F-actin intensity of the PSM surface cells region (D) or PSM internal cells region (E) in the anterior and posterior PSM from three embryos. Each dot represents a transverse section for which the mean F-actin signal within the surface cells or internal cells was measured and normalized by the average intensity of the signal in the posterior sections of the same embryo. Sample size: n = 24 sections (anterior PSM) and 25 sections (posterior PSM). ***p<0.0005 using a T-test. (D) Anterior vs posterior, p=5.62e-7. (E) (D) Anterior vs posterior, p=7.7e-4.