Jukka Jernvall

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Mammalian dentition consists of teeth that develop as discrete organs. From anterior to posterior, the dentition is divided into regions of incisor, canine, premolar and molar tooth types. Particularly teeth in the molar region are very diverse in shape. The development of individual teeth involves epithelial-mesenchymal interactions that are mediated by(More)
The main morphological features of the mammalian tooth crown are cusps, but the developmental mechanisms that cause the formation of cusps are unknown. Tooth cusp formation commences at cap-stage with the appearance of the enamel knot, which is a cluster of non-dividing epithelial cells. In this study, enamel knot was first seen in embryonic mice molar(More)
The enamel knot, a transient epithelial structure, appears at the onset of mammalian tooth shape development. Until now, the morphological, cellular and molecular events leading to the formation and disappearance of the enamel knot have not been described. Here we report that the cessation of cell proliferation in the enamel knot in mouse molar teeth is(More)
Primates tend to be long-lived, and, except for humans, most primate females are able to reproduce into old age. Although aging in most mammals is accompanied by dental senescence due to advanced wear, primates have low-crowned teeth that wear down before old age. Because tooth wear alters crown features gradually, testing whether early dental senescence(More)
Unlike humans, who have a continuous row of teeth, mice have only molars and incisors separated by a toothless region called a diastema. Although tooth buds form in the embryonic diastema, they regress and do not develop into teeth. Here, we identify members of the Sprouty (Spry) family, which encode negative feedback regulators of fibroblast growth factor(More)
One motivation in the study of development is the discovery of mechanisms that may guide evolutionary change. Here we report how development governs relative size and number of cheek teeth, or molars, in the mouse. We constructed an inhibitory cascade model by experimentally uncovering the activator-inhibitor logic of sequential tooth development. The(More)
The study of mammalian evolution depends greatly on understanding the evolution of teeth and the relationship of tooth shape to diet. Links between gross tooth shape, function and diet have been proposed since antiquity, stretching from Aristotle to Cuvier, Owen and Osborn. So far, however, the possibilities for exhaustive, quantitative comparisons between(More)
Mammalian tooth forms are produced during development by folding of the enamel epithelium but the molecular mechanisms involved in the formation and patterning of tooth cusps are not understood. We now report that several key signaling molecules found in well-known vertebrate signaling tissues such as the node, the notochord, the apical ectodermal ridge,(More)
The relationship between the genotype and the phenotype, or the genotype-phenotype map, is generally approached with the tools of multivariate quantitative genetics and morphometrics. Whereas studies of development and mathematical models of development may offer new insights into the genotype-phenotype map, the challenge is to make them useful at the level(More)
Mammalian tooth crowns have precise functional requirements but cannot be substantially remodeled after eruption. In developing teeth, epithelial signaling centers, the enamel knots, form at future cusp positions and are the first signs of cusp patterns that distinguish species. We report that ectodin, a secreted bone morphogenetic protein (BMP) inhibitor,(More)