Fig. 2. Irregular cell shapes, but normal apical-basal epithelial cell organisation in grh mutants. (A,D) Confocal projections of a DT segment of wild-type (A) and grh mutants (D) labelled with antibodies against DE-cad to visualise the apical cell circumference. The tracheal cell shapes in grh mutants are irregular and elongated compared to the wild type. (B,C,E-L) Confocal longitudinal sections of one segment of the DT, to visualise the subcellular localisation of apical, lateral and cytoskeletal markers in wild-type and grh mutant embryos. Embryos carrying the cytoplasmic trh-lacZ marker (B,E) were double labelled with antibodies against ß-gal (green) and Crumbs (red). The levels and subcellular localisation of Crumbs at the apical cell surface is the same in wild-type (B) and grh mutants (E). Double labelling of wild-type (C) and grh (F) embryos with anti-DE-cad (red) and anti-Nrx IV (green) shows that cadherin is localised more apically than Neurexin both in grh mutants and in wild-type embryos. Labelling for ß-heavy spectrin (G,J) shows concentrated localisation at the apical surface of the tracheal cells, both in wild-type (G) and grh mutants (K). Wild-type (H) and grh mutants (J) expressing UAS-Act-GFP in all tracheal cells were labelled with GFP. The apical localisation of actin-GFP is not affected in grh mutants. Wild-type (I) and grh mutants (L) carrying the trh-lacZ reporter were double labelled for ß-gal (green) and Coracle (red). The lateral membrane localisation of Coracle is not affected by grh. Scale bar: 5 µm.