Electron microscopy of cross-sections of dissected Aedes aegypti salivary glands. A. Electron micrograph using cytochemical techniques. Anterior portion of the proximal lateral lobe showing a cell with the nucleus (Nu) located basally in the cytoplasm, a developed rough endoplasmic reticulum (RER) and finely granular secretory material. Additional features indicated are: secretory cavity (Sc); mitochondria (arrow) and invaginations (I). B-F. Micrographs produced using conventional electron microscopy. B. Middle portion of the proximal lateral lobe showing electron-dense cells, Nu in the basal region of the cell and a large amount of mitochondria (arrows) and secretory vesicles (arrowheads). C. The distal portion of the lateral lobe showing cells with Nu and little condensed chromatin, prominent nucleoli and elongated and rounded mitochondria (arrows). The Sc has many invaginations of the membrane with fine and electron-dense secretions. The salivary duct also is indicated (asterisk). D. Electron micrograph of cells from the distal-lateral lobe. The cells contain a concentration of RER and large Nu with prominent nucleoli. Sc contain dark homogeneous secretions and membrane invaginations. E. Proximal portion of the medial lobe showing large and central Nu and the presence of many mitochondria (arrows) associated with basal membrane invaginations. The salivary duct also is indicated (asterisk). F. Electron micrograph of cells from the distal region of the medial lobe. The Nu has little condensed chromatin and the cytoplasm has dispersed RER cisternae with rectilinear and irregular organization. The Sc have irregular borders.