The Hoxd3 gene is transcribed to yield mRNA (Bedford et al. 1995, Tan et al. 1996, Spitz et al. 2001, Chai et al. 2009). Hoxd3 mRNA is observed in the neural tube with an anterior boundary at the junction of rhombomeres 4 and 5 (Bedford et al. 1995) and in the dorsal root ganglia, first cervical vertebra, thyroid gland, kidney tubules, esophagus, stomach, and intestines (Tan et al. 1996).