FIG. 3.

Caudal pharyngeal pouch derivatives normally formed in homozygous mutant mice. (A and B) Whole-mount in situ hybridization of wild-type (+/+) and homozygous mutant (−/−) embryos using a Pax9 probe. The arrowheads show the pharyngeal pouches (I to IV). Scale bars = 0.5 mm. (C) Normal formation of the thymus in a homozygous mutant neonate. Hematoxylin and eosin (H&E) staining was used. tm, thymus. Scale bar = 300 μm. (D) Normal histology of the parathyroid gland in a homozygous mutant mouse (5 months old). H&E staining was used. tr, thyroid gland; pt, parathyroid gland. Scale bar = 100 μm. (E) Parafollicular cells in the mutant thyroid gland (5 months old), indicated by arrowheads. H&E staining was used. Scale bar = 50 μm.