Fig. 1. Dorsal thoracic region of nec null mutant fly (nec²/nec¹⁹). Within a few hours of eclosion, adult flies develop black cuticular patches that are associated with cellular necrosis of the underlying epithelial cells (Green et al., 2000). Necrotic patches are randomly distributed over most of the body surface, but occur preferentially at the proximal leg joints (arrows). Distal leg segments have been dissected away.