Malpighian tubules of adult flesh fly, Sarcophaga ruficornis Fab. (Diptera: Sarcophagidae): an ultrastructural study.

The Malpighian tubules of adult flesh fly, Sarcophaga ruficornis consist of principal and stellate cells. The principal cells reveal all the characteristics of transporting epithelia with well developed deep basal membrane infoldings forming a complex of interconnecting labyrinth of canaliculi and luminal microvilli, both of which are associated with mitochondria. The central cytoplasm of the cells contains a well developed nucleus, clear vacuoles or vacuoles filled with secretory material, mineral concretions or spherocrystals, lysosomes and a network of endoplasmic reticulum. The mineral concretions are also observed in the region of luminal microvilli and in the lumen of the tubule suggesting their extrusion into the lumen by exocytosis. Several formed bodies are also observed in the lumen. Stellate cells are characterized by simple membrane infoldings and luminal microvilli devoid of mitochondria. The cells are separated by septate junctions. The Malpighian tubules are richly supplied by tracheae and muscle fibers.