Fig. 5. (A,C) Segmental plate recipients fixed 24 hours after surgery and processed for myf5 expression. (B,D) Vibratome sections from the embryos shown in A and C at the planes indicated. Myf5 is activated on a normal trunk timetable, which is earlier than is appropriate for head muscles. (E,F) Adjacent sections from a stage 20 segmental plate recipient. Graft-derived cells within a somite-like condensation synthesize MyHC, nearly a day earlier than it would be found in developing head muscle cells.