develops from specialized Malpighian tubule cell Malpighian tubule Type II cell fly_anatomy.ontology These cells are involved in primary urine production via the presence of ion channels that allow chloride and water to enter the tubule lumen (O'Donnell et al., 1998). Malpighian tubule stellate cell FBbt:00005797 Morphologically distinct cell type found only in the initial, transitional and main segments of the Malpighian tubules interspersed with Type I cells. Type II cells are smaller and flatter than Type I cells, with shorter (main segment) or no (initial region) apical microvilli. Type II cells originate from a subset of caudal visceral mesoderm cells that overlie the tubule primordia as they evert from the hindgut. By stage 15, Type II cells have been incorporated in the tubules and adopt epithelial characteristics. In the mature tubules there are on average 110 Type II cells. excretory star cell CL:1000155 SC Malpighian tubule Type II cell primordium visceral trunk mesoderm derivative