Dental stem cells during development of vertebrate dentitions

Vertebrate dentition is a dynamic structure, which continuously renews its elements, the teeth. Continuous tooth renewal is enabled thanks to the presence of epithelial and mesenchymal dental stem cells. Epithelial stem cells are located in the dental lamina, which, together with the adjacent mesenchyme, takes part in regulation of the stem cells through a complicated signalling network. This network is responsible for the positioning, correct amount, inactivity, proliferation and differention of the stem cells. Vertebrate dentitions are morphologically diverse. However, their development is, to a certain extent, controlled by shared evolutionarily conserved mollecular mechanisms. For example, epithelial stem cells of all vertebrate groups examined so far express the transcription factor Sox2 and are shown to be regulated by signalling pathways, such as Wnt/β-catenin, Shh, Fgf and Bmp. Due to the rich diversity in dental lamina morphologies, the locations of presumptive stem cells correspondingly differ among vertebrates. This thesis summarizes current knowledge on dental stem cells in each lineage to identify shared and derived aspects of vertebrate dentitions