The purpose of this work was to investigate the basis of early dorsiventrality of the leaf and to determine what effects mature dorsiventral leaf characteristics, such as collateral bundles or lamina with adaxial palisade parenchyma and abaxial spongy parenchyma. Dorsiventrality was expressed initially by the differentiation of the primordium into two areas, one abaxial and the other adaxial, in contact with each other. From this contact and through meristematic activity arise the collateral bundles and the lamina. Any significant injury to the primordia caused total or partial disappearance of the more delicate adaxial area and, consequently, total or partial lack of collateral bundles and (or) lamina. This modification led to the development of various abnormal leaves, such as centric organs, scyphi, and leaves with round-tipped lobes. Minor injuries restricted to the abaxialndash;adaxial contact could induce lamina teratogenesis in the form of organoid enations. These results indicate that this contact controls the organogenesis of the lamina.
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