Omb overexpression causes autonomous and non-autonomous cellular retraction. Tubα1>omb clones are marked by strong anti-Omb staining (green). (A) Omb overexpressing cells tend to scatter in the epithelium. Thus, mosaic discs generally contain few cases of grouped cells (arrow). These show central retractions. (A') x-z scan through a retracting clone. (B and C) Enhanced generation of Omb overexpressing cells by more severe heat shock conditions causes clustering of wild type cells into groups with smooth outlines (arrowheads). In these non-clonal wild type cell groups, cellular retraction occurrs in the periphery (B') or in the center (C'). (A-C) are x-y scans, (A'-C') x-z scans. Arrows in A to C indicate the cell clusters that are shown in A' to C'.