Fig. 7. Expression of Msx1, Bmp4 and Tbx22 in the developing palatal shelves is not altered in the Osr2^{tm1Jian/tm1Jian} homozygous mutant embryos. (A,B) At E14.5, Msx1 mRNA is abundantly expressed in medial maxillary processes and the tooth mesenchyme and weakly expressed in the anterior palatal shelves (arrows) in both wild-type (A) and the homozygous (B) mutant embryos. Note the palatal shelves are retarded in the homozygous mutant (arrows in B). (C,D) At E13.5, Bmp4 mRNA is expressed at comparable levels in wild-type (C) and the homozygous mutant (D) palatal shelves. (E,F) At E13.5, Tbx22 mRNA is abundantly expressed in the palatal mesenchyme and the base of the tongue in both wild-type (E) and the homozygous mutant (F) embryos. Tbx22 is also expressed similarly in the periocular mesenchyme in wild-type and the mutant embryos. mx, maxillary process; t, tongue.