title: Early regression of the dental lamina underlies the development of diphyodont dentitions.
abstract: Functional tooth germs in mammals, reptiles, and chondrichthyans are initiated from a dental lamina. The longevity of the lamina plays a role in governing the number of tooth generations. Monophyodont species have no replacement dental lamina, while polyphyodont species have a permanent continuous lamina. In diphyodont species, the dental lamina fragments and regresses after initiation of the second tooth generation. Regression of the lamina seems to be an important mechanism in preventing the further development of replacement teeth. Defects in the complete removal of the lamina lead to cyst formation and has been linked to ameloblastomas. Here, we show the previously unknown mechanisms behind the disappearance of the dental lamina, involving a combination of cell migration, cell-fate transformation, and apoptosis. Lamina regression starts with the loss of the basement membrane, allowing the epithelial cells to break away from the lamina and migrate into the surrounding mesenchyme. Cells deactivate epithelial markers (E-cadherin, cytokeratin), up-regulate Slug and MMP2, and activate mesenchymal markers (vimentin), while residual lamina cells are removed by apoptosis. The uncovering of the processes behind lamina degradation allows us to clarify the evolution of diphyodonty, and provides a mechanism for future manipulation of the number of tooth generations.
authors.affiliation: Institute of Animal Physiology and Genetics, v.v.i., Academy of Sciences of the Czech Republic, Veveri 97, 602 00 Brno, Czech Republic. buchtova@iach.cz
authors.forename: M
authors.initials: M
authors.lastname: Buchtová
authors.forename: J
authors.initials: J
authors.lastname: Stembírek
authors.forename: K
authors.initials: K
authors.lastname: Glocová
authors.forename: E
authors.initials: E
authors.lastname: Matalová
authors.forename: A S
authors.initials: AS
authors.lastname: Tucker
mesh_terms: D000818:Animals; D017209:Apoptosis; D015820:Cadherins / Q000378:metabolism; D002465:Cell Movement; D019229:Dentition, Permanent; D004847:Epithelial Cells / Q000166:cytology; D058750:Epithelial-Mesenchymal Transition; D007633:Keratins / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D009805:Odontogenesis / Q000502:physiology; D020598:Proto-Oncogene Proteins c-myb / Q000378:metabolism; D000071250:Snail Family Transcription Factors; D013552:Swine; D013556:Swine, Miniature; D014083:Tooth Germ / Q000166:cytology / Q000196:embryology*; D014094:Tooth, Deciduous; D014157:Transcription Factors / Q000378:metabolism; D014746:Vimentin / Q000378:metabolism
chemical_list: D015820:Cadherins; D020598:Proto-Oncogene Proteins c-myb; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; D014746:Vimentin; D007633:Keratins; D020778:Matrix Metalloproteinase 2