Developmental regulation of dental regeneration and morphogenesis in Fishes

The study of odontogenesis has been limited by the lack of established developmental models which regenerate their teeth continuously throughout life. Furthermore, our understanding of dental morphogenesis is primarily based on research on the mouse. Evolutionary developmental biology seeks to comparatively study natural morphological diversity in order to identify the developmental mechanisms which underpin their evolution. Throughout this thesis, I investigate the process of dental morphogenesis and successional regeneration in both cartilaginous fishes (Chondrichthyes) and bony fishes (Osteichthyes), in order to provide a more detailed picture of the evolution of odontogenesis, and a reference point for the comparative study of dental regeneration in humans.

I show that odontogenesis is widely conserved from sharks through to mammals, and that the most usual vertebrate dentitions develop from only subtle modification of the ancestral bauplan. Furthermore, the process of dental regeneration appears to be important, not only for the replacement of lost or damaged dentition, but also in the evolution of dental morphological diversification. Given that successional dental regeneration is an ancestral gnathostome characteristic, I also investigate the regulation of dental regeneration in a basal gnathostome lineage. Our de novo transcriptome sequencing and predictive gene regulatory network analysis reveals novel candidate markers involved in the regulation of successional dental regeneration, previously undescribed during odontogenesis. This thesis lays the groundwork for the comparative study of these novel markers in mammalian models.