Shoot apex organization during the early establishment growth phase. (A) Shoot apex median longitudinal section stained with PAS-NBB from a 3-month-old plant. Inset: the corresponding plant used for the shoot apex preparation. (B, C) Confocal microscopic views of longitudinal (B) and transverse (C) sections of shoot apices stained with propidium iodide from 3-month-old plants. Abbreviations: *, meristematic dome; L1, tunica cell layer; P1–P2–P3, leaf primordia. Scale bars: (A, C) = 100 µm; (B) = 50 µm; (inset in A) = 10 cm.