3. Hand-cut cross-section of a fresh C. citratus young leaf sheath washed with ethanol and acetone, and then stained with Schiff’s reagent.
A, Transmitted light. B, Epifluorescence of the same section under blue light excitation. Conditions as in Fig. 2B. Arrows indicate the oil cells.
No citral can be detected in oil cells after extraction (A), but the fluorescent cell wall is still clearly discernible (B). V, Vascular bundle.