Cell proliferation in the developing palate in WT, Fgfr2b_/_, and Fgf10_/_ mice. (A_H) BrdU analysis of E12 palate. (A_F) Histological sections of BrdU staining. Compared to that in WT animals, proliferation in Fgfr2b_/_ and Fgf10_/_ mutants was reduced in all areas analyzed. This was significant in all epithelial readings, and in general the reduction was greater in Fgfr2b_/_ compared with Fgf10_/_ mutants. (I_P) BrdU analysis of E13 palate. (I_N) Histological sections of BrdU staining. Proliferation rates were significantly reduced in all epithelial areas analyzed except in Fgf10_/_ mutants in the bend region at the junction of the nasal aspect of the palatal shelf and the cranial base. Mesenchymal proliferation rates were also reduced in both mutants, though not to the degree seen in the epithelium. (I) BrdU incorporation was particularly noticeable in the groove between the maxilla and the palatal process (arrow). All sections are the same magnification; scale bar, 200 ∝m. The y axes in G, H, O, and P indicate the mean values of BrdU incorporation of each area assayed. Error bars represent standard deviation; asterisk denotes a significant finding (P < 0.005) compared with the WT value. In A and L, dotted lines indicate length of epithelium measured, and green and yellow areas indicate the mesenchymal areas assayed in the apex (a) and bend (b) regions. Ant, anterior; Post, posterior.