Against the background of what is known on the acquisition of mammalian tooth shape and its control and on the structure and development of teleost teeth, we want to address the question of what determines tooth shape in teleosts. Within this broad frame, a number of separate questions can be addressed :how does tooth shape change during ontogeny? Are differential mitotic activities and distribution of apoptoses responsible for different tooth shapes? How do spatiotemporal patterns of gene expression differ in tooth germs of different shape? What do the msx genes in eretmodines teach us on the evolution of tooth shape?