Transmission electron micrographs showing the ultrastructure of the chloroplast at different stages in flag leaves (A-F) and exposed peduncles (G-P). (A, G and H): stage 1; (B, I and J): stage 2; (C, K and L): stage 3, (D, M and N): stage 4; (E, F, O and P): stage 5. (H), (J), (L), (N) and (P): higher magnification of the area highlighted in (G), (I), (K), (M) and (O), respectively. Stages 1-5 correspond (respectively) to the end of anthesis, the milk-development stage, the soft dough-development stage, the hard dough-development stage and the ripening stage. Bars: (A-D), 2 μm; (E, G, I, K, M, O), 5 μm; (F, H, J, L, N, P), 1 μm. CW, cell wall; En, envelop; G, granum; Mt, mitochondrion; Pg, plastoglobuli; S, starch; Th, thylakoid.