Fig. 4. Mmy is required for uniform tracheal tube growth. (A-C) Lateral view of wild-type and mmy mutant embryos labelled with the tracheal lumen-specific antibody 2A12. The 2A12 antibody marks the lumen of wild-type (A) and mmy^IL07 mutant (B) tracheae. The dorsal trunks (DTs) of mmy^IL07 embryos are slightly convoluted compared with wild type. The tracheal lumen of mmy^IK63 mutant embryos fails to label with 2A12 (C). (D) Expression of the pan-tracheal lacZ marker 1-eve-1 in mmy^IK63 mutants and labelling with anti-ß-gal reveal a correctly patterned tracheal network in these mutants, but some of the narrower ganglionic and dorsal branches are discontinuous (arrow indicates a dorsal branch gap). (E-G) Confocal analysis of two or three DT segments in embryos that carry the pan-tracheal lacZ marker 1-eve-1, doubly labelled with 2A12 (red) and ß-gal (green). In stage 15 mmy^IK63 mutants (F), the DT fusion branches fail to expand (arrowheads); at stage 16 (G), the DTs develop severe constrictions and dilations, when compared with the wild type (E). Scale bars: 50 µm in A-D; 10 µm in E-G.