Ca-HGO expression in the leaf and stem of 3-month-old Camptotheca acuminata plantlets. Paraffin-embedded cross sections of leaves (A and B) and primary body of the stem (C and D), treated with Ca-HGO antisense (A and C) and sense (B and D) digoxigenin-labelled probes. The hybridization signals in the leaf treated with antisense probe (A) are present in all mesophyll cells. In the stem treated with antisense probe (C), hybridization signals are present in parenchyma cells associated with vascular bundles (black arrows). No hybridization signals are present in the sections of leaf (B) and stem (D) treated with sense probe. Abaxial Epidermis (AbE); Adaxial Epidermis (AdE); Palisade Parenchyma (PP); Spongy Parenchyma (SP). Bar = 50 μm.