F. 2. Hand-cut cross-section of a fresh C. citratus young leaf blade stained with Schiff’s reagent. A, Transmitted light. The red stained cells
(arrows) are oil cells accumulating citral. B, Epifluorescence of the same section. Blue light excitation at 450–590 nm, using a Zeiss barrier filter
LP 520. Photosynthetic tissues fluoresce red. Oil cells show conspicuous lignified cell walls. C, Epifluorescence of the same section. UV-light
excitation at 365 nm, using a Zeiss barrier filter LP 420. Citral containing oil cells (arrows) display noticeable fluorescent cell walls. B, Bundle
sheath ; V, vascular bundle.