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Fibroblast growth factor receptor 1 in skeletal and heart muscle cells: Expression during early avian development and regulation after notochord transplantation

Basic fibroblast growth factor (bFGF, FGF‐2) mediates several biological functions during embryonic development. With regard to skeletal muscle formation, it has been suggested that FGF‐2 is involved in the growth and differentiation of myogenic precursor cells. To identify the FGF‐responsive cells we studied the expression of FGF receptor type I (FGFR‐1) during early embryonic development of the chick. FGFR‐1 immunoreactivity is present at all stages examined (embryonic day [E] 2‐E5). Expression of FGFR‐1 is found in the somite myotome, limb bud muscle cells, eye and tongue muscle cells, and myocardium. Transplantation of an additional notochord into the paraxial mesoderm, which prevents the formation of a myotome, reveals the absence of FGFR‐1 immunoreactivity on the operated side. The distinct expression pattern of FGFR‐1 in migrating and differentiating muscle cells indicates that in addition to the stimulation of proliferation of myoblasts, FGF‐2 exerts other (nonmitogenic) effects on postmitotic myocytes. © 1996 Wiley‐Liss, Inc.