Homozygous clones in the tracheal system of third instar larvae result in terminal cells in which a gas-filled lumen is only seen in the most proximal part of the cell, in contrast to wild type where a gas-filled lumen can be detected throughout the whole cell. Lumen is present in some of the terminal branches in which no gas-filling is detected, but these lumens are thinner than normal, their diameter is irregular and they do not form continuous networks. Mutant cells occasionally contain multiple lumens within one branch. In autocellular branches, the presence of homozygous cells results in gaps in gas-filling. Again, the lumen is partially present in the gaps, and has a variable diameter and irregular shape. The penetrance of the terminal tracheal cell phenotype is 100%, while the penetrance of the gaps in gas-filling in the autocellular branches is 70%. The gas-filling defect is first seen in mutant second instar larvae, where only part of the main tracheal branch is filled with gas, despite the formation of side branches.

Giant lipid droplets accumulate in midgut cells in homozygous larvae.

Homozygous clones induced at the late blastoderm/early gastrulation stage and then examined in the third larval instar tracheal system lack a lumen either throughout the cell or in major parts of the cell in clonal terminal cells and clonal cells in secondary branches.

Homozygous embryos do not show gaps in the tracheal system.