Radially patterned morphogenesis of murine hair follicle placodes ensures robust epithelial budding.

The bending of simple cellular sheets into complex three-dimensional (3D) forms requires developmental patterning cues to specify where deformations occur, but how positional information directs morphological change is poorly understood. Here, we investigate how morphogen signaling and cell fate diversification contribute to the morphogenesis of murine hair placodes, in which collective cell movements transform radially symmetric primordia into bilaterally symmetric tubes. Through live imaging and 3D volumetric reconstructions, we demonstrate that Wnt and Shh establish radial patterns of cell fate, cell morphology, and movement within developing placodes. Cell fate diversity at different radial positions provides unique and essential contributions to placode morphogenesis. Further, we show that downstream of radial patterning, gradients of classical cadherin expression are required for efficient epithelial rearrangements. Given that the transformation of epithelial discs into 3D tubes is a common morphological motif used to shape diverse organ primordia, mechanisms of radially patterned morphogenesis are likely highly conserved across evolution. [Display omitted] • Cell fates within hair follicle primordia emerge in a radial pattern • Wnt gradients and Shh radially pattern cell fate, shape, adhesion, and motility • Radial position and fate determine cell morphology and morphogenetic behavior • Radial adhesion gradients promote cell rearrangements, driving placode polarization Leybova et al. utilize live imaging and 3D reconstructions to uncover a radial pattern of cell fate, morphology, adhesion, and motility in developing hair follicle primordia. Radial patterning is established by graded Wnt signaling and Shh and is necessary for the complex morphogenetic changes that drive placode budding and polarization. [ABSTRACT FROM AUTHOR]