Figure 4.2.

Different stem cell populations regulate normal epidermal homeostasis. Schematic representation of the different stem cell population found within different skin compartments. (A) Different lineage tracing experiment have shown that the IFE is maintained by the presence of K14⁺ progenitor basal cells that are able to generate the differentiated lineages that comprise the squamous epithelium of the skin. (B and C) Within the pilosebaceous unit, a slow cycling SC residing in the bulge is able to give rise to all the different HF lineages and regenerate a new hair follicle during anagen. They can also contribute to the IFE after wounding and to the SG population that is usually maintained by a resident pool of Blimp1⁺ slow-cycling residing progenitors. (D) In the sweat gland, a K14⁺ progenitor was shown to be able to regenerate a full functioning gland capable of sebum production. Finally, within the touch dome structure (E), K17⁺ slow-cycling cells have been shown to give rise to K18⁺ rapid-cycling progenitor that can further generate differentiated progeny.