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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
Author(s) -
Mendelson Jeri Kersten,
Smoller Bruce R.,
Mendelson Bruce,
Horn Thomas D.
Publication year - 2000
Publication title -
journal of cutaneous pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 75
eISSN - 1600-0560
pISSN - 0303-6987
DOI - 10.1034/j.1600-0560.2000.027002061.x
Subject(s) - integrin , extracellular matrix , dermis , fibronectin , anatomy , myocyte , biology , pathology , microbiology and biotechnology , myosin , vitronectin , connective tissue , cell , medicine , genetics
The arrector pili (AP) muscle is a small band of smooth muscle that attaches proximally to the bulge area of the pilosebaceous apparatus in the reticular dermis and extends up toward the epidermis. The distal anatomy of the AP and the anchorage mechanism allowing hair erection have not been previously described. Integrins are likely candidates mediating this attachment. Immunohistochemical techniques were used to determine the distribution of the following integrins: α1, α2, α3, α4, α5, α6 and β1 as well as fibronectin. Frozen human scalp tissue was sectioned in traditional planes, obliquely and horizontally to visualize microanatomy in three dimensions. Histological examination revealed that the distal portions of smooth muscle fibers splay extensively between collagen bundles of the upper dermis. Integrin subunits α1, α5 and β1 were expressed by the AP muscle. Analysis of the relative density of immunoreactivity in digitized sections revealed increased α5 subunit expression at the extracellular matrix (ECM)‐muscle interface. These data suggest that anchorage of the AP muscle to the ECM is via α5β1 integrin and α1β1 integrin functions in muscle cell‐cell adhesion. Extensive splaying of smooth muscle fibers may allow increased surface area contact between the ECM and smooth muscle cells expressing peripherally situated α5 integrin.