Fig. 3. msx2cre;Ift88^fl/n mice show no phenotype but prx1cre;Ift88^fl/n mice develop polydactyly. (A-D) Images of the dorsal (A,B) and ventral (C,D) surfaces of the hindlimbs of wild-type (A,C) and msx2cre;Ift88^fl/n conditional mutant (B,D) adult mice. No defects in limb patterning were visible in the conditional mutants. (E-H) Alizarin Red and Alcian Blue staining of forelimbs (E,F) and hindlimbs (G,H) from wild-type (E,G) and prx1cre;Ift887^fl/n conditional mutant (F,H) mice at E18.5. Forelimbs of prx1cre;Ift88^fl/n (F) develop eight or more nonpatterned digits. While the forelimb exhibited extensive polydactyly, the hindlimb (H) typically showed a duplication of digit I (asterisk). (I) Alizarin Red-stained forelimb of wild-type (bottom) and prx1cre;Ift88^fl/n (top) conditional mutant at postnatal day 11. The proximodistal length of the limbs is shortened in conditional mutants, but the patterning of the long bones is largely unaffected. Anterior is up in all panels.