First published online December 28, 2004
Development 132, 203e (2005)
© The Company of Biologists Limited
Touching a nerve in tooth development
Although there are times when we may wish our teeth lacked nerves, these
nerves are required for the function and protection of our teeth. On p.
323, Kettunen and
co-workers reveal that the expression of semaphorin 3a (Sema3a), a secreted
repulsive axon guidance molecule, coordinates axon navigation and patterning
with the formation of the first mandibular molar in mice. First, the
researchers use knockout mice to show that Sema3a is essential for early tooth
innervation. Then, in tissue recombination experiments, they show that Wnt4
expressed by early oral and dental epithelium induces Sema3a
expression in the molar mesenchyme before the first nerve fibres arrive. Later
on during the axon navigation of dental pioneer nerves, Wnt4 and Tgfß1
together control Sema3a expression in the dental mesenchyme. Thus,
epithelial-mesenchymal interactions in developing teeth provide the
instructions for the formation of their nerve supply.

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Related articles in Development:
- Coordination of trigeminal axon navigation and patterning with tooth organ formation: epithelial-mesenchymal interactions, and epithelial Wnt4 and Tgfß1 regulate semaphorin 3a expression in the dental mesenchyme
- Päivi Kettunen, Sigbjørn Løes, Tomasz Furmanek, Karianne Fjeld, Inger Hals Kvinnsland, Oded Behar, Takeshi Yagi, Hajime Fujisawa, Seppo Vainio, Masahiko Taniguchi, and Keijo Luukko
Development 2005 132: 323-334.
[Abstract]
[Full Text]