Étude comparée de l'ultrastructure des stomates ouverts et fermés chez le Tradescantia virginiana

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Abstract
Guard cells and subsidiary cells of Tradescantia virginiana L. were examined with transmission and scanning electron microscopy. No plasmodesmata occur in the walls between the guard cells and the subsidiary cells. The numerous mitochondria suggest that guard cells are very active. Numerous small vacuoles were observed in closed stomata, whereas few and large vacuoles were present in opened stomata. A specialized peripheral reticulum and some invaginations containing cytoplasm were observed in chloroplasts of opened stomata. This increase of effective surface of the membrane presumably allows a rapid exchange of substances to or from the chloroplast. This was not observed in mesophyll plastids. The structures described are discussed in relation to guard cell physiology.