Morphological and biochemical analyses of the salivary glands of the malaria vector, Anopheles darlingi

Adult Anopheles darlingi salivary glands are paired organs located on eithe r side of the esophagus. The male glands consist of a single small lobe. Th e female gland is composed of two lateral lobes, with distinct proximal and distal portions, and a medial lobe, The lobes are acinar structures, organ ized as a unicellular epithelium that surrounds a salivary canal. The gener al cellular architecture is similar among the lobes, with secretory materia l appearing as large masses that push the cellular structures to the periph ery of the organ. Cells of the proximal-lateral lobes show asynchronous cyc les of secretory activity and contain secretory masses with finely filament ous aspect. In the distal-lateral lobes, cells display synchronous cycles o f activity, and have a dense secretory product with mottled pattern. Cells of the medial lobe have secretory masses uniformly stained and highly elect rondense. Biochemical analysis of the adult female salivary glands revealed apyrase, alpha-glucosidase and lysozyme activities. Alpha-glucosidase and lysozyme activities are detected mostly in the proximal lobes while apyrase is mainly accumulated in the distal lobes. This differential distribution of the analyzed enzymes reflects a specialization of different regions for sugar and blood feeding. Thus, the morphological differences observed in th e lobes correlate with functional ones.