High resolution

Module 8: Figure epidermal stem cell

Control of epidermal stem cell proliferation.

Proliferation of epidermal stem cells located in the bulge region of the hair follicle (Module 7: Figure skin cells) are inhibited by both the SMAD signalling pathway, which is activated by bone morphogenetic protein (BMP) and by the presence of various inhibitors (Dkk1, WIF1 and sFRP) that block the Wnt signalling pathway activated by the frizzled receptor (Fz). As the dermal papilla are drawn up towards the bulge during the follicle hair cycle they release Noggin and Wnt that act to drive proliferation by reversing these inhibitory mechanisms.