Meeting Abstract

14.5  Wednesday, Jan. 4  Changing Tissue Properties and Cell Behavior During Tooth Organogenesis MOUSTAKAS, Jacqueline E*; KALLONEN, Aki; AHTIAINEN, Laura; HÄKKINEN, Teemu; 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; Institute of Biotechnology, University of Helsinki, Finland; Institute of Biotechnology, University of Helsinki, Finland; Institute of Biotechnology, University of Helsinki, Finland; Department of Physics, University of Helsinki, Finland; Institute of Biotechnology, University of Helsinki, Finland jacqueline.moustakas@helsinki.fi

The mammalian dentition is a model system in which to study the developmental mechanisms of morphological change. Teeth develop through an epithelial-mesenchymal interaction between oral ectoderm and neural crest-derived mesenchyme. Models of the tooth development predict a role for mechanical forces in the growth of the epithelium, and therefore, in the formation of shape. Far less is known about the cellular behaviors and properties of the mesenchyme in this process. First, we examined the growth dynamics of the mesenchyme during the development of mouse molars using computed tomography. We generated three-dimensional reconstructions of the embryonic teeth and found that whereas mesenchymal density declines during morphogenesis, the mesenchyme underneath developing cusps retain high density. Next, to examine the cellular basis of the density dynamics, we used reporter mouse technology to monitor cell division and cell movements in cultured teeth. We found that the cells underneath the developing cusps are more stationary relative to each other than at the base. Together with molecular data on cell adhesion molecules, these results implicate mesenchyme to participate in tooth shape patterning by forming a physically heterogeneous template for the folding epithelium.