The gene that defines the localization of the tooth germs is:

  # The gene that defines the localization of the tooth germs is:

A. FGF-8

B. BMP-2

C. Dlx-5

D. Pax-9

The correct answer is D. Pax-9.

During tooth development, several mesenchymal molecules and their receptors act as mediators of epithelial - mesenchymal interactions. Bone morphogenetic proteins (BMPs) 2,4,7 mRNAs shift between epithelium and mesenchyme during regulation of tooth morphogenesis. Fibroblast growth factor (FGF8, FGF9) have been localized in the dental mesenchyme and act via downstream factors MSX1 and PAX9. Muscle specific homeobox genes MSX-1 and Msx-2, appear to be involved in epithelial mesencymal interactions and craniofacial development, particularly in the initiation of developmental position (Msx-1) and further development (Msx-2) of tooth buds.Pax-9 is transcription factor necessary for tooth morphogenesis.