Figure 3.

DR5::GUS expression in pre-procambial and procambial cells. Four-DAG first rosette leaf primordium. A, Extremely low DR5 expression in elongated procambial cells of I1° in the basal part and somewhat stronger expression in younger apical sections of I1°. Frames indicate magnified areas in B and C. B, Low, heterogenous DR5 expression cells of I3°. Note that these cells are still isodiametric in shape and cannot anatomically be distinguished from surrounding cells. C, Strong, homogenous DR5 expression in cells of I2°s, some of which have divided to form double rows of narrow procambial cells (outlined). Scale bar = 50 μm. DIC optics.