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 microanatomy of the distal arrector pili (AP) muscle and its anchorage to the extracellular matrix (ECM), focusing on the role of integrins. Using immunohistochemical techniques on 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 ECM was mediated by α5β1 integrin, while α1β1 integrin was involved in muscle cell-cell adhesion. The study also noted that the extensive splaying of smooth muscle fibers increased the surface area contact between the ECM and smooth muscle cells, which expressed α5 integrin.