Cell division, elongation and differentiation of the conducting tissue. The photo was taken with the help of a fluorescence microscope. The section is stained with PAS (periodic acid - Schiff's reagent) that has a specificity for polysaccharides. Consequently, it stains cell walls, nuclei, starch grains (S: statolith starch) and polysaccharide-containing secretions. The apex is surrounded by a calyptra ( C ). The cells of the root cap (V) secrete a gelatinous material, the mucigel. The cells of the apical root meristem (W) are very small. Calyptra and epidermis develop from the same initials, the primary bark and the stele from others. The stele contains the vascular elements that begin to differentiate. The size of all cells increases, they elongate in parallel to the longitudinal axis. The increase in size is especially conspicuous in the cells of the vascular elements (R. KAPPLER, 1984).