Fig. 3. Loss of IFT52 function leads to multiple defects in embryogenesis. (A) Wild type IFT52 encodes for a protein of 356 amino acids. In the first mutant line (XL826), the N-terminal 257 amino acids of IFT52 are fused to ß-galactosidase protein. In the second mutant line (RRJ295), the N-terminal 309 amino acids of IFT52 are fused to ß-galactosidase protein. (B) A wild-type E10.5 embryo has round smooth mesencephalic flexure (outlined). (C) An Ift52^hypo E10.5 embryo has tight mesencephalic flexure (outlined). (D) The heart tube in wild-type embryo loops to the left. (E) The heart tube in Ift52^hypo loops to the right. (F) The left and right olfactory pits (red arrowheads) and maxillary arches (blue arrowheads) are separated at E10.5 in wild-type embryos but are fused in the ventral midline in Ift52^hypo E10.5 embryos (G). Broken lines in F,G outline the ventral boundaries of the mandibular processes. (H) A limb bud of wild-type E12.5 embryo with five digits (white arrowheads). (I) A limb bud of Ift52^hypo mutant with six digits (white arrowheads). (J) Ptch1 expression in an E10.5 wild-type limb bud. (K) Ptch1 expression is not detectable in an E10.5 Ift52^hypo limb bud.