c-Kit-negative fibroblast-like cells express platelet-derived growth factor receptor α in the murine gastrointestinal musculature

Platelet-derived growth factor receptors (PDGFRs) belong to the same kinase group as c-Kit receptor tyrosine kinase that is specifically expressed in the interstitial cells of Cajal (ICC) in the gastrointestinal tract. In this study, we examined PDGFR alpha immunoreactivity in the murine gastrointestinal tract. PDGFR alpha-immunopositive (PDGFR alpha-ip) cells were observed in the musculature in all parts of the gastrointestinal tract. Although PDGFR alpha-ip cells were distinct from ICC and neurons, these cells were closely associated with intramuscular ICC and enteric nerve fibers. In the myenteric layer, PDGFR alpha-ip cells formed a cellular network with their ramified processes and encompassed myenteric ganglia. Numerous PDGFR alpha-ip cells were observed in the subserosal plane and showed a multipolar shape. The distribution pattern of the PDGFR alpha-ip cells in the ICC-deficient W (v) /W (v) mutant mice was the same as that in normal mice. PDGFR alpha-ip cells that showed intense immunoreactivity of SK3 potassium channel were considered to correspond to fibroblast-like cells or non-Cajal interstitial cells. Our observations suggest that PDGFR alpha-ip cells are basic cellular elements throughout the gastrointestinal musculature and are involved in the gastrointestinal functions.