Fig. 4. Isolation of the meristem from all primordia but P₁ leads to wider leaves. (A) Control tomato apex in top view. The approximate delimitation of the meristem is represented by a circle. The arc encompassed by the primordia is represented by thickened portions of the circles. (B) Top view of a meristem 2 days after its isolation. Note the increased lateral width of P₁ and I₁ (compare with A). (C) Meristem as shown in B, with I₂ becoming visible as a small bulge (white arrowhead). (D) An oversized P₁ primordium with two tips, one week after isolation of the meristem. (E) Control apex shown in A showing the direct contact neighbours of P₁ (P₃ and P₄) and of I₁ (P₂ and P₃). P₄, P₃ and P₂, indicate the bases of pre-existing leaf primordia that were removed at the beginning of the experiment, and P₁ represents the youngest primordium; I₁, I₂ and I₃ indicate primordia formed after the ablation. Scale bar: 100 µm.