Morphometric analysis of the midgut of female Aedes aegypti (L.) (Insecta, Diptera) under various physiological conditions.

Autor(es): Hecker H; Brun R; Reinhardt C; Burri P H

Resumo: The ultrastructure of the midgut of Aedes aegypti females was investigated by means of morphometric techniques. The interest was focussed on quantitative differences in the composition of epithelial cells between the anterior (A) and posterior (P) part of the midgut. The aim was to attribute defined functions to each of these 2 parts. 5 different physiological stages were compared: 1 = immature female; 2 = ready for first blood meal (b.m.); 3 = digestion of b.m.; 4 = ready for 2nd b.m.; 5 = aging female. Whereas in stage 1, when the gut has not yet reached a functional state the epithelial cells of A and P resemble each other, distinct differences develop in subsequent stages. Generally the cell volume and the nuclear-cytoplasmic ratio become higher in P than in A. Concomitantly the mitochondrial content and the surface area of the rough endoplasmic reticulum are more prominent in P than in A. On the other hand more microvilli, a more extensive basal labyrinth and a well developed smooth endoplasmic reticulum are present in A. Enlarged cytoplasmic volumes, especially high in P, are found 24 h after the first b.m. (stage 3). In accordance with this increase the volume of organelles and/or their membrane surface areas also reach maximal values. This augmentation of the metabolic cell apparatus suggests that during blood digestion the whole organ develops an increased functional capacity. From the quantitative structural differences in A and P we concluded that the A-part of the midgut is especially involved in absorption. To the P-part more protein synthesis may be attributed, thus indicating an enhanced formation of digestive enzymes. Although this study deals with a rather specialised insect (blood digestion), it appears that our hypothesis attributing functions to defined midgut zones, agrees to a certain extent with the "secretion-absorption-model" of Berridge (1970).

Palavras-Chave: Aedes aegypti; Midgut epithelium; Cytology; Morphometry; Electron microscopy

Imprenta: Cell and Tissue Research, v. 152, n. 1, p. 31-49, 1974

Identificador do objeto digital: 10.1007/BF00224209

Descritores: Aedes aegypti - Cell ; Aedes aegypti - Public health

Data de publicação: 1974