Mutant alleles of scr, SCRƊND, and its target genes have defects in root epidermal cells and ground tissue patterning. Cross-section images show Toluidine Blue-stained root tips of 8-d-old seedlings in the wild type (A), scr-3 (B), SCRpro:SCR(∆ND)-GFP/scr-4 (C), br6ox2-1 (D), br6ox2-2 (E), mgp (F), nuc (G), and rlk (H). Black arrows indicate the darkly stained hair cells (H cells) at N positions, and red arrows indicate the lightly stained nonhair cells (N cells) at H positions. Red asterisks indicate the original cortical cells, and orange asterisks indicate the additional cortical layer. Bar in C = 20 μm and applies to all other micrographs.