Fig. 3. Spindle orientations in the wing. (A) Third instar wing imaginal disc, stained for -tubulin (green), ap-lacZ (red), and DNA (blue). Arrows indicate examples of dividing cells at the DV boundary, bars mark their axis of division. This can occur at different orientations relative to the DV boundary. (B) Histogram showing the percent of spindles at the DV boundary (blue bars, out of 86 total) or away from the DV boundary (red bars, out of 456 total) found in different orientations relative to the boundary. The angle was defined by the axis of the spindle and the tangent of the nearest DV interface. Angles were binned into 15° increments, thus a random distribution would predict 16.7% of spindle orientations (one sixth of the total) in each bin (dashed line). There is a slight bias for cells at the boundary to divide parallel to it, but not enough to account for compartmentalization.