Spatiotemporal switches in progenitor cell fate govern upper hair follicle growth and maintenance

The epidermis provides a protective barrier against hostile environments. However, our knowledge of how this barrier forms during development and is subsequently maintained remains incomplete. The infundibulum is a cylindrical epidermal tissue compartment that serves as an outlet for hair follicles protruding from the skin and the excretion of the sebaceous glands that are essential for proper skin function. In this study, we applied quantitative fate mapping to address how infundibulum are maintained during adulthood. We demonstrate that progenitors build and maintain tissues through stochastic cell fate choices. Long-term analysis identified a preferential transient contribution from cells initially located at the bottom of the structure to the maintenance of the tissue, with bursts of local progenitor expansion associated with the phases of hair growth. Beyond providing compartment-wide insights into progenitor cell dynamics in infundibulum, these findings demonstrate how spatiotemporal regulation controls transient progenitor dominance.