Fig. 1. Anatomy of wild-type and ral1 mature embryos and plants. (A-E,K,M-P,U,W) Wild type. (F-J,L,Q-T,V,X) ral1. (A-C,F-H) Longitudinal sections through a mature embryo showing details of the embryonic axis (A,F), the shoot apical region (B,G) and the basal region of the scutellum (C,H). Note that the absence of vasculature in F and G, as compared with A and B, is due to the fact that in ral1 the plumule lies slightly off the median plane. (D,I) Detail of the dorsal region of the scutellum in a transverse section through a mature embryo 180 µm below the scutellum tip. (E,J) Schematic representation of a median longitudinal section through a mature embryo (left) and of a dorsal view of a mature embryo (right). The embryonic provascular system is shown in green. (K,L) Region between two large veins in a transverse section through the middle of a mature leaf blade. (M,Q) Midrib region in a transverse section through the middle of a mature leaf blade. Arrows in M indicate the veins of the wild type that are missing in ral1. (N,R) Detail of the upper right-hand corner in M and Q, respectively. (O,S) Detail of the large vascular bundle of the midrib in M and Q, respectively. (P,T) Detail of transverse sections through the apical region of the first internode showing details of the internode wall. (U,V) Transverse section through an adventitious root 12 mm from the root tip. (W,X) Detail of the vascular cylinder in U and V, respectively. Toluidine Blue-stained granules in F,G,I showed typical blue-brown staining with iodine solution (not shown), revealing ectopic starch formation. bs, bundle sheath extension; lv, large vein; mp, metaphloem; mx, late metaxylem element; p, plumule; r, radicle; s, scutellum; sc, sclerenchyma; sv, small vein; v, provascular tissue. Scale bars: (A,F) 150 µm (B,D,G,I,K,L,N,O,R,S) 50 µm (C,H,M,Q,P,T,U,V) 100 µm (W,X) 25 µm.