Meeting Abstract

P1.48  Tuesday, Jan. 4  Tooth Cusps Feel The Force MOUSTAKAS, Jacqueline E.*; KALLONEN, Aki; HARJUNMAA, Enni; SALAZAR CIUDAD, Isaac; HäMäLäINEN, Keijo; JERNVALL, Jukka; Institute of Biotechnology, University of Helsinki, Finland; Department of Physics, University of Helsinki, Finland; Institute of Biotechnology, University of Helsinki, Finland; Universitat Autònoma de Barcelona, Spain; Department of Physics, University of Helsinki, Finland; Institute of Biotechnology, University of Helsinki, Finland Jacqueline.Moustakas@helsinki.fi

Teeth are one of the model systems to study epithelial organ formation, and the relative roles of the epithelium and the mesenchyme in shaping organs. Teeth develop through an epithelial-mesenchymal interaction between oral ectoderm and neural crest-derived mesenchyme. Tooth shape is controlled by epithelial signaling centers, the enamel knots, via differential growth and folding of the epithelium. Enamel knots form at the places of future cusps, the prominences that are the basic units of the tooth shape. Whereas models of tooth development predict a role for the mesenchyme in pushing the epithelium to form cusps, empirical evidence is lacking. Empirical data has shown that the enamel knots produce signaling molecules that stimulate the proliferation of the underlying mesenchyme. We examined the growth dynamics of the mesenchyme during the development of mouse molars to test whether the mesenchyme has a passive or an active role in shaping the tooth epithelium. Using computed tomography, we measured the density of mesenchyme as a proxy for force by the mesenchyme on the dental epithelium. We then generated three-dimensional reconstructions of the embryonic teeth to test whether differences in mesenchymal density could predict epithelial morphogenesis and the formation of tooth cusps, and whether these patterns agree with computational simulations of tooth organogenesis.