The microanatomy of the distal arrector pili: possible role for α1β1 and α5β1 integrins in mediating cell‐cell adhesion and anchorage to the extracellular matrix

The study investigated the distal anatomy of the arrector pili (AP) muscle and its anchorage mechanism, which had not been previously described. Using immunohistochemical techniques on frozen human scalp tissue, the researchers identified the expression of integrin subunits α1, α5, and β1 in the AP muscle. The findings suggested that the anchorage of the AP muscle to the extracellular matrix (ECM) was mediated by α5β1 integrin, while α1β1 integrin played a role in muscle cell-cell adhesion. The extensive splaying of smooth muscle fibers was proposed to increase the surface area contact between the ECM and smooth muscle cells, facilitated by the peripheral expression of α5 integrin.