Epidermal Cells Expressing Putative Cell Markers in Nonglabrous Skin Near the Distal End of the Arrector Pili Muscle

In a 2016 study, researchers examined the distribution of epidermal stem cells in nonglabrous skin, focusing on their proximity to the distal end of the arrector pili muscle (APM). They discovered that a specific group of basal keratinocytes expressing stem cell markers such as K15, MCSP, and α6 integrin are situated in a niche at the lowest part of the rete ridges near the APM attachment site. The study, which used skin specimens from six adult mice, supported the idea that these stem cells are organized hierarchically rather than randomly, potentially contributing to skin renewal and stability. The findings also suggested that the APM might be involved in maintaining the stem cell niche, which could have implications for understanding skin disorders like nonmelanoma skin cancer.