Fig. 16. The relationship between fork length and the density of myogenic progenitor cells staining with antibodies to (A) Pax 7, (B) FoxK1- and (C) Myogenic Regulatory Factors (black and white symbols represent MyoD and red symbols Myf-5) in the fast muscle of the progeny of PL-morphs (triangles) and LB-morphs (circles) of Arctic charr. The fish were reared at either cold constant temperatures (2.2–3.2°C) or at more variable warmer temperatures (4–7°C).