Figure 2.

Localisation of AsA with methanolic AgNO₃ in courgette and celery tissues. The left side of each image shows sections stained immediately after excision and the right side control sections which were pre-incubated in 5% (w/v) CuSO₄ to oxidise endogenous AsA. Transverse section of courgette fruit (Ai) shows intense staining in the region of the outer vascular ring (arrows). Staining was also observed in the region surrounding developing seeds. Detail of the outer vascular area confirms that staining was confined to vascular regions (Aii). Staining was absent in control sections pre-incubated with 5% CuSO₄. In the celery petiole (Bi) intense staining was associated with vascular bundles (arrows) and storage parenchyma (tail-less arrows). Detail of the vascular region (Bii) shows intense staining associated with the phloem but not the xylem.