Fig. 6. Cell division patterns in developing leaf primordia. (A,E) Transverse sections through seedling meristems (M) including plastochrons (P) 1-3. (A) The wild-type leaves have 5 cell layer margins at P₂ and P₃ (asterisk). (E) Xcl1 P₂ and P₃ margins have disorganized cell layers and are thicker than normal. (B-D) Serial sections through a wild-type P₄ margin with protoderm divisions (arrowhead) in the anticlinal plane and vascular bundles (V) near margin. (F-G) Serial sections through an Xcl1 P₄ margin showing oblique periclinal divisions (arrows) in the protoderm and normal anticlinal divisions (arrowheads). Scale bars A, E, 100 µm; B-D and F-H, 25 µm.