Fig. 1: The evolution of the new cusps in the mouse upper molar involved changes in the whole dynamics of cusp patterning. | Nature Communications

Fig. 1: The evolution of the new cusps in the mouse upper molar involved changes in the whole dynamics of cusp patterning.

From: Comparative transcriptomics in serial organs uncovers early and pan-organ developmental changes associated with organ-specific morphological adaptation

Fig. 1

a Drawings of the epithelium and mesenchyme compartments at four stages of molar development: at “bud” stage, an epithelial signalling centre called PEK (Primary Enamel Knot) triggers the formation of a “cap” defining the future crown. Between “cap” and “crest” stage, SEKs (Secondary Enamel Knots) are patterned sequentially in the epithelium and drive cusp formation. By the end of morphogenesis, the mesenchyme has the shape of the future tooth and the epithelium is a dental impression. b Final shapes, dynamic and pattern of cusp addition in mouse and hamster lower and upper molars. Sides: Upper views of final morphologies represented by 3D scans. Supplementary cusps in mouse upper molars highlighted in orange. Panels: Series of developing molars (dots) hybridized against Fgf4 to reveal signalling centres. Time series were modelled using Markov processes as a series of stages with specific durations (blue bars). x-axis: developmental age, y-axis: morphological stages, with schematized SEK arrangements. Dotted lines: homology of early cap and crest stage. Orange, blue and grey arrows show 3 differences in hamster and mouse upper molars.

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