Initial determination, budding and elongation of Malpighian tubules during stage 13-14 is normal in rols5a homozygous embryos. However rearrangement of tubule cells to produce elongated, 2 cell wide tubules is delayed (from stage 15 to stage 16-17) and partially disrupted. Tubule migration is defective from stage 15. The anterior tubules follow an erratic path through the body cavity, sometimes doubling back to form loops, and never form the wild-type kink in A2/3. Stellate cell (excretory star cell) integration into the Malpighian tubules appears normal in these embryos.
Unlike most other rols alleles, rols5a mutants do not exhibit fusion of somatic or visceral muscles.