Fig. 7. Myogenin expression in a 46-somite embryo reared at 8°C. (A) Sagittal section showing the accumulation of myogenin transcript in the caudal somites and the decrease in transcript expression in the more rostral somites. (B–E) Transverse sections, arranged most posterior first, showing the decrease in transcript expression in progressively older (more rostral) somites. n, notochord; g, gut. The arrowhead indicates somites. Scale bars, 300 µm.