ATOMIC-FORCE MICROSCOPY STUDY OF ISOLATED IVY LEAF CUTICLES OBSERVED DIRECTLY AND AFTER EMBEDDING IN EPON(R)

The first results obtained by atomic force microscopy (AFM) of the fin e structure of isolated ivy leaf cuticles are reported. Observations o f transverse sections embedded in Epon(R) allow easy recognition of th e general shape of cuticles as viewed by light microscopy. The surface profile shows irregularities not revealed by transmission electron mi croscopy (TEM). The lamellate and reticulate zones, distinguishable by TEM, were also located by AFM. The outer zone appears as an irregular ly thick (c. 4 mu m) homogeneous region; lamellae can be visualized on ly after image-processing to subtract relief defects produced by secti oning. The second region or internal zone represents the largest part of the cuticle thickness; it appears heterogeneous and disordered. The cuticle internal surface images show imprints of the epidermal cells. At high magnification, the cell imprint central regions appear to be made up of a network of fibres of c. 50 nm diameter. Some images show that these fibres have a preferential orientation. They disappear afte r acid-hydrolysis is used to eliminate polysaccharides. This study sho ws that AFM can produce reproducible images of isolated plant cuticles at a subcellular scale leading to new high-resolution representations of cuticle substructure.