Fig. 3. Septate junctions (SJs) are defective in mmy mutant epithelia. (A-C) TEM-analysis of septate junctions (SJs) of wild-type, mmy^IL07 and mmy^IK63 mutant larval (end of stage 17) epidermal cells. The SJs of the wild-type (A) and mmy^IL07 mutant (C) epidermal cells are seen as ladder-like structures. In mmy^IK63 mutant epidermal cells (B), this ladder-like assembly is absent, but electron-dense intercellular material at the position usually occupied by the SJ is present. (D-G) Fas3 (red) is occasionally mislocalised in mmy^IK63 mutant epithelia. In wild-type (D) hindgut epithelia, Fas3 concentrates within the apical-most region of the lateral membrane, whereas in mmy^IK63 mutants (E) Fas3 is found along the entire lateral cell surface. Fas3 localisation is similarly affected in the mmy^IK63 mutant salivary gland (G) when compared with the wild type (F). Scale bars: 0.125 µm in A-C; 5 µm in D-G.