Ultrastructural and cytochemical studies on the developing adhesive disc of Boston Ivy tendrils

Ultrastructural observations of the immature adhesive disc from tendrils of Boston Ivy showed that the peripheral cells, which are the presumptive contact layer, contain vacuoles of varied sizes which are filled with electron-dense aggregates. In small vacuoles, these deposits were appressed to the tonoplast and fusion of these small vacuoles with the large vacuoles apparently occurs. Cells from the central zone were largely parenchymatous. The vacuoles of many of these parenchyma cells contained electron-dense spheres and hemispheres of material either appressed to the tonoplast or within the vacuole lumen. In these cells, the vacuole-cytoplasm interface was characterized by a filiform network of interconnected membranes. Positive reactions with reagents for the identification of polyphenols indicate that the vacuoles of nearly all the peripheral cells and scattered cells of the central zone contain tanniniferous substances. Insoluble carbohydrates also occur in the vacuoles of the peripheral cells, but they contain little or no protein or lipid.