MISEK, I.; Inst. of Anim. Physiol. and Genet., Brno, CZ: Differences and correspondences in segmentation of the dental lamina in mammals

The evolutionary principles surrounding the development of eutherian dentitions has not been fully clarified. There are some differences as well as correspondences in the dental development of aquatic mammals relative to terrestrial mammals. Morphologically, the dentition of aquatic mammals is often much closer to the functional polyodont, homodont, polyphyodont dentition of reptiles than to the typically diphyodont, oligodont, heterodont dentition that chatacterizes most terrestrial mammals. We have compared the segmentation of the dental lamina of five representative mammalian orders (insectivors, chiropters, rodents, artiodactyls, and cetaceans) using Sterba’s comparable prenatal stages (Sterba, 1995) and routine histological sectioning, immunohistochemistry, and 3-D aided reconstruction methods. It appears that the dental lamina originates in a similar manner in all species under investigation but that its subsequent segmentation differs in some ways. Results of such comparative embryological studies should contribute to a fuller understanding of which of the theoretical models for the evolution of heterodontia in mammals corresponds closest to reality. This work was supported by the Grant Agency of the Czech Republic (grant 304/02/0448) and the Ministry of Education, Youth and Sports of the Czech Republic (COST Programme B23, OC B23.001).