title: [Action of crystals of Bacillus thuringiensis var. israelensis on the midgut of Aedes aegypti L. larvae, studied by electron microscopy].
abstract: Ingestion of Bacillus thuringiensis var. israelensis crystals by Aedes aegypti larvae is followed by midgut epithelium disruption. Earliest ultrastructural changes consist of an enlargement of intra- and intercellular spaces in the basal region of the cell. Endoplasmic reticula disintegrate by forming spherical structures which increase in size during intoxication. Mitochondria are transformed at first into a condensed form, then become swollen with the disappearance of internal cristae. In the cardia cells, which secrete the peritrophic membrane, the Golgi apparatus may produce electron-dense secretion vesicles; in this event, the peritrophic membrane assumes an abnormal configuration. Before complete breakdown, a cellular hypertrophy is observed: few cells become balloon-like. At the same time, the microvilli decrease in size, widen and then disappear after a few hours exposure to crystal delta-endotoxin.
mesh_terms: D000330:Aedes / Q000382:microbiology* / Q000648:ultrastructure; D000818:Animals; D001413:Bacillus thuringiensis / Q000502:physiology*; D004064:Digestive System / Q000382:microbiology; D007814:Larva; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning
vernacular_title: Action des cristaux de Bacillus thuringiensis var. israelensis sur l'intestin moyen des larves de Aedes aegypti L., en microscopie électronique.