Fig. 7. bab specifies tarsal segment morphology. The tarsal region of the prothoracic leg of a male fly is shown in A,C,E,G, and the metathoracic leg in B,D,F,H. (A) Wild-type prothoracic leg showing a sex comb and transverse bristle rows only on TS1. (B) Wild-type metathoracic leg showing transverse bristle rows on TS1 and TS2. (C,D) bab^PR72/bab^PR72 mutants (strong hypomorphic) show sex comb bristles and transverse bristle rows on TS1-TS3, and a fusion between TS5 and TS4. (E-H) Df(3L)Fpa1/Df(3L)Fpa2 mutants show the bab null phenotype. Tarsal segments are strongly shortened and thickened. Although the bristle pattern of TS2-4 is transformed, the ectopic sex combs on TS2 and TS3 are smaller than in a hypomorphic mutant (E) or are missing altogether (G), and the TS1 sex comb is smaller than in wild type (E). Tarsal fusion extends further proximally, often leading to a fusion of TS5 to TS2 (F,G). Kinks and abnormal bristle arrangements (H) or loss of distal segments are frequently seen in metathoracic tarsi. In all panels, distal is towards the left; numbers 1-5 mark TS1-TS5; arrows indicate sex combs; arrowheads indicate transverse bristle rows; an angled line points to tarsal segments that are fused rather than connected by joints.