Fig. 4.

Novel pharyngeal skeleton morphologies in Hoxa3^zf/zf and Hoxa3^mz/mz mice, and skeletal phenotype of compound mutants with Hoxd3. (A–D) Lateral views of the throat cartilages in cleared newborn skeletal preparations. Anterior is up, dorsal is to the right. Asterisk indicates the lesser horn of hyoid; hy, greater horn of hyoid; thy, thyroid cartilage; crc, cricoid cartilage. (Scale bar: 500 μm.) In Hoxa3^null/null (^−/−), Hoxa3^zf/zf (zf/zf), and Hoxa3^mz/mz (mz/mz), the greater horn is malformed and fused to the thyroid cartilage (black arrows in B–D). (B) In the null, the lesser horn of the hyoid is greatly reduced or deleted. (C and D) The zf/zf and mz/mz mutants have distinct hyoid morphologies, and are different from WT or null. White arrows show extra cartilage structures in these mutants. (E–J) Lateral views of the cervical region in cleared skeleton preparations of the indicated genotypes for Hoxa3 (a3) or Hoxd3 (d3). Anterior is up, dorsal is to the left. Exoccipital (eo) bone, atlas (at), axis (ax), and anterior arch of atlas (arrowhead) are indicated. Note that G and J are similar, whereas I is more similar to H than to F. (Scale bar: 1 mm.)