Ultrastructural analysis of the midgut of Drosophila auraria larvae. Morphological observations and their physiological implications

Abstract

Electron and light microscopic examinations of Drosophila auraria larval midguts derived from insects of various stages of development show six clearly differentiated regions along its monolayered epithelium. Generally, the morphological data indicate that the cells of all these regions are involved in the elaboration and secretion of products in a manner that appears to follow the generally accepted scheme for these events. Among the six regions, the posterior and the anterior sections of the midgut are the regions that could be considered as the first and second most important sites, respectively, for terminal digestion and the absorption of nutrients. The middle midgut, on the other hand, in which long infoldings of the basal plasma membrane of the cells are observed, can be considered as a region of intense water transport between the hemolymph and the central lumen of the midgut.