Expression of green fluorescent protein (GFP) in Tg ( myf 5(80K):GFP) transgenics matches the dynamic pattern of endogenous myf5 expression in cranial muscles. (A-D) GFP fluorescence is apparent in pectoral fin muscle (pm), dorsal rostral muscle (drm), and hypaxial muscle (hy). (C-E) GFP fluorescence is detected in the occipital somite (os; precursors of sternohyoideus, sh) and some cranial muscles, such as the superior oblique (so) and inferior oblique (io). (F-H) Endogenous myf5 transcripts are also detected in cranial muscles, including so and io by whole-mount mRNA in situ hybridization. (A,C,F) Side views, rostral to the left, dorsal to the top; (B,D,G) dorsal views, rostral to the left; (E,H) ventral views, rostral to the left. Scale bars: 200 μm.