Electron microscopic evidence for plasmodesmata in dicotyledonous guard cells.

In Nicotianna tobaccum and Vicia faba leaves, plasmodesmata were observed by electron microscopy in walls between sister guard cells and walls between guard and epidermal cells. The latter were found primarily in pit fields of anticlinal walls and showed considerable complexity as evidenced by branching. Cytologically, the plasmodesmata appear functional in operative guard cells and should be considered in the mechanism of stomatal movements.