Fig. 6. Anti-Phospho-Smad and Bmpr2 labeling reveals Bmp responsive cells. (A) Schematic showing the pattern of Bmp4 expression in olfactory placode (OP) first branchial arch (1BA) and otic vesicle (OV) of an E9.5 mouse embryo (Dudley and Robertson, 1997). The approximate region of tissue shown in B-E is indicated by the red boxes. (B) Anti-phospho-Smad labeling (green) of E9.5 mouse section in the region of the first branchial arch (1BA) and olfactory placode (OP). Intense labeling is observed in the epithelia of both structures. A merge of (B) with Hoechst nuclear labeling (blue) is shown in C. The turquoise color of nuclei in (C, red arrowheads) indicates nuclear phospho-Smad immunoreactivity. (D) Bmpr2 immunoreactivity in sections of E9.5 mouse first branchial arch (1BA) and olfactory placode (OP). Cell-surface labeling is apparent in the cells of the epithelia (red arrowheads) and more faintly in the underlying mesenchyme. A merge of (D) with Hoechst labeling (E) shows that, as would be expected for cell-surface labeling, the nuclei do not change color. (F) Anti-phospho-Smad labeling (green) of E12.5 mouse eye sections showing the lens vesicle (LV) and anterior optic cup rim (broken red line) on the nasal side (N). A nuclear pattern of labeling is observed in lens cells at the equator (red arrowheads) faintly in the more posterior presumptive primary lens fiber cells (white arrowheads) and in the optic cup rim. A merge of F with Hoechst nuclear labeling (G, blue) gives turquoise color nuclei thus confirming nuclear phospho-Smad labeling. (H) Bmpr2 immunoreactivity in sections of E11.5 mouse eye. Cell-surface labeling is apparent in the cells at the lens vesicle (LV) equator (red arrowheads) and in the cells of the developing retina and presumptive RPE. A merge of (H) with Hoechst labeling (I) shows that, as would be expected for cell-surface labeling, the nuclei do not change color.