The outer surface morphology and the ultrastructure of grape berries during
growth were examined by electron microscopy, The cuticle began to form bef
ore anthesis as highly organized and tightly appressed cuticular ridges. Du
ring the period of rapid expansion, the cuticular material spread out over
the grape berry. At the same time, an outer wax layer of about 0.5 mum was
indentified, As growth proceeded, the cuticular material flattened out and
eventually disappeared. At the final stage of growth, the berry had a smoot
h, continuous and homogeneous cuticle with a thickness of 3 mum.