Meeting Abstract

P1.61  Monday, Jan. 4  Protein expression of genes that may be involved in initiating and developing the secondary dentition in mammals ARMFIELD, Brooke A. *; THEWISSEN, J.G.M.; VINYARD, Christopher J.; Department of Anatomy and Neurobiology, Northeastern Ohio Universities Colleges of Medicine and Kent State Biomedical Science; Rootstown, Ohio. bgarner@kent.edu

Limited tooth replacement is a defining trait of mammals, however, very little is known about the genetic pathways involved in the development of a second generation of teeth. Mice, the mammalian model for genetic studies, only have a single generation of tooth development and, therefore, researchers have not been able to determine the signals that initiate and generate the morphology of the second dentition in mammals. We examine Sus scrofa as a model for mammalian secondary tooth development. Pig embryos were chosen because they replace all their teeth (excluding their adult molars) and staged embryos are relatively easy to obtain. To explore gene expression patterns during formation of the second generation, we looked at an array of genes (Bmp4, Fgf8, Fgf4 Shh, Pax9, Msx1 and β-catenin) involved in primary tooth development or hypothesized to be involved in mammalian tooth replacement. Immunohistochemistry was used to define areas of protein expression during several stages of pig tooth development (gestation days 24-65). We found that several of the genes known to influence the first dentition, such as Bmp4, Fgf8 and Shh, were present in the oral and dental epithelium during secondary tooth formation. We are currently investigating if their expression and that of β-catenin, a gene associated with inducing supernumery tooth development, differ from patterns observed in mice. Given the functional and phylogenetic significance of the second generation of mammalian teeth, these results will contribute to our understanding of mammalian life history and evolution.