Segmentation-gene mutants are missing parts of segments

Classes of Drosophila segmentation-gene mutants. These diagrams depict representative gap, pair-rule, and segment-polarity mutants. The red trapezoids are the dense bands of exoskeleton seen in Figure 13-13. The boundary of each segment is indicated by a dotted line. The left-hand diagram of each pair depicts a wild-type larva, and the right-hand diagram depicts the pattern formed in a given mutant. The shaded light orange regions on the wild-type diagrams indicate the domains of the larva that are missing or affected in the mutant.