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. 2020 Dec 30;9:e60432. doi: 10.7554/eLife.60432

Figure 10. Model of positional acquisition of nascent hair cells (HCs) in the neuromast.

Figure 10.

Unlike scenarios 1 and 2 illustrated in Figure 1C, our results show a model in which an end-stage HC precursor before division expresses low levels of emx2 (light pink). After the precursor divided, Notch signaling mediated through the Notch ligand (green color) and Notch1a receptor (red color) generates asymmetry between the two sibling HCs. This asymmetry results in stochastic specification of anterior (PIa) and posterior (PIp) positional identity (PI) to sibling HCs, which includes regulation of emx2 expression. Thus, an emx2-positive, Pla-HC formed at the posterior position undergoes positional exchange with its sibling Plp HC, whereaswhen an emx2-positive, Pla-HC formed in the anterior position, the two sibling HCs do not exchange positions. In addition to the delay in apical protrusion mediated by Emx2, the Rock and Roll is also regulated by the intercellular core planar cell polarity (cPCP) pathway (asterisk).