Fig. 9.3-3. Transverse section of stem of wormwood (Artemisia). The duct in this wormwood stem is large, well-defined and easy to see. The epithelium cells all have abundant, darkly-stained contents, indicating a high concentration of cytoplasm and a low level of vacuolation. This is fairly strong evidence that the epithelium cells themselves are secretory, but it is also possible for secretory cells to be so vacuolate that they almost appear empty. This type of duct is very common; you will encounter it in many species.