Morphology and ultrastructure of the Malpighian tubules of Rhyacophila Italica MORETTI larvae (Trichoptera, Rhyacophilidae).

Larvae of Rhyacophila italica Moretti have six malpighian tubules in the form of long, simple,blind-ending tubes, which open between the midgut and the hindgut, and float in the hemocoel. The malpighian tubules were studied using light and electron microscopy. They consist of a single layer of cells enclosing a central lumen in which urine is formed and flows towards the hindgut. The lumen varies in diameter along the tubule, being wider in the proximal portion. The cells lay on a basement lamina, surrounded by fine tracheoles. There are primary cells and secondary (stellate) cells. The primary cells have a large nucleus and the cytoplasm is rich in mitochondria and endoplasmic reticulum; these cells are characterized by long, apical microvilli and deep basal infoldings. The secondary cells are flat with shorter, well-spaced microvilli and the cytoplasm lacks concretions.