Lipophilic glandular trichomes form secretory vesicles that accumulate in a distended noncellular secretory cavity . Imidazole-buffered osmium tetroxide solution was used to visualize unsaturated lipids in glands of Cannabis sativa. This method of staining revealed two kinds of secretory vesicles in the cavity of glands. Some smaller and rounded vesicles in the secretory cavity and secretory cells were positively stained with the imidazole, and they appeared electron-dense. The other type of vesicles which have bigger sizes more or less were not reacted, however, they appeared transparent. A high contrast of the cuticles which cover the gland was also strongly reacted with that processing. Those result suggest that the dark vesicles in the cavity may contribute to enlarge the subcuticular wall and cuticle when contents of these vesicles are dispersed into wall.