Ultrastructural features of the midgut epithelium of females Lutzomyia intermedia (Lutz & Neiva, 1912) (Diptera : Psychodidae : Phlebotominae)

A morphological study of the midgut of Lutzomyia intermedia, the primary ve ctor of cutaneous leishmaniasis, in southeast Brazil, was conducted by ligh t, scanning and transmission electron microscopy The midgut is formed by a layer of epithelium of columnar cells on a non-cellular basal lamina, under which there is a musculature, which consists of circular and longitudinal muscular fibers. A tracheolar network is observed surrounding and penetrati ng in the musculature. Females were examined 12, 24, 48, 72 h and 5 days fo llowing a blood meal and were analyzed comparatively by transmission electr on microscopy with starved females. In starved females, the epithelium of b oth the anterior and posterior sections of the midgut present whorl shaped rough endoplasmic reticulum. The posterior section does not present well-de veloped cellular structures such as mitochondria. Observations performed at 12, 24, 48 and 72 h after the blood meal showed morphological changes in t he cellular structures in this section, and the presence of the peritrophic matrix zip to 48 h after the blood meal. Digestion is almost complete and a few residues are detected in the lumen 72 h after blood feeding. Finally, on the 5th day after the blood meal all cellular structures present the or iginal feature resembling that seen in starved sandflies. Morphometric data confirmed the morphological observations. Mitochondria, nuclei and microvi lli of midgut epithelial cells are different in starved and blood fed femal es. The mitochondria present a similar profile in the epithelium of both th e anterior and posterior section of the midgut, with higher dimension in st arved females. The cell microvilli in the posterior section of the midgut o f starved females are twice the size of those that had taken a blood meal. We concluded that there are changes in the midgut cellular structures of L. intermedia during the digestion of blood, which are in agreement with thos e described for other hematophagous diptera.