c-Kit-negative fibroblast-like cells express platelet-derived growth factor receptor alpha 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 PDGFRalpha immunoreactivity in the murine gastrointestinal tract. PDGFRalpha-immunopositive (PDGFRalpha-ip) cells were observed in the musculature in all parts of the gastrointestinal tract. Although PDGFRalpha-ip cells were distinct from ICC and neurons, these cells were closely associated with intramuscular ICC and enteric nerve fibers. In the myenteric layer, PDGFRalpha-ip cells formed a cellular network with their ramified processes and encompassed myenteric ganglia. Numerous PDGFRalpha-ip cells were observed in the subserosal plane and showed a multipolar shape. The distribution pattern of the PDGFRalpha-ip cells in the ICC-deficient W(v)/W(v) mutant mice was the same as that in normal mice. PDGFRalpha-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 PDGFRalpha-ip cells are basic cellular elements throughout the gastrointestinal musculature and are involved in the gastrointestinal functions.