Lateral migration of the mesoderm fails to occur in some regions along the anterior-posterior axis in stage 9 mutant embryos, resulting in holes in the layer of mesodermal cells at stage 11. Homozygous clones in the wing disc are often associated with duplications of the anterior wing margin, outgrowths of the wing, ectopic margin bristles in the wing blade and occasional wing nicks. The ectopic margins are always mirror-image dorsal-dorsal margins and the wing outgrowths always originate from the dorsal surface. Homozygous clones in the leg disc results in a shortened leg with loss of joints between tarsal segments.