Fig. 4

The observations of the epidermis of lip base with flat callus from transmission electron microscopy (TEM) showing: a a few residues of secreted materials on the cuticle surface, especially between radial cell walls, thick outer tangential cell walls. b magnification of a, ruptured cuticle caused by the accumulation of secretion beneath. c heterogeneous (lipoid and phenolic) nature of secretion. d periplasmic space occurred, dense osmiophilic cytoplasm with organelles and vesicles (white arrows), the central vacuole with vesicles with osmiophilic content (asterisks). e periplasmic spaces with few vesicles, flocculent material, and globules with osmiophilic material. f vesicles in periplasmic space and in electron-dense cytoplasm, and osmiophilic, phenolic content in the vacuole. cw—cell wall, m—mitochondrion, n—nucleus, ph—phenolic content, ps—periplasmic space, RER—rough endoplasmic reticulum, va—vacuole, ve—vesicle