Abstract
The reporter gene encodes enzymes whose activities are visable by staining with a chromogenic substrate. The reporter gene is developmentally neutral as proved by the normal developmental potential of LacZ positive embryos. In order to clarify the early expression of the myogenin-LacZ gene during mouse embryogenesis, transgenic mice harboring the reporter gene linked to the myogenin flanking region have been developed. Stereoscopic visualization of LacZ expression of these transgenic mouse F1 embryos revealed that the LacZ gene expression in rostral somites appeared to correspond to myogenin which was first detected in mesodermal tissues at high levels at 8.0 days p.c. (post coitum), Which is the furthermore, LacZ expression in the somites and in the limb bud was observed at 10.5 days p.c. and 11.5 days p.c. respectively. At 12.5 days p.c., LacZ gene expression in cells started to migrate to the ventral region of the embryo, where eventually LacZ gene-expressed cells formed the abdominal musculature. This suggested that the role of the myogenin gene is crucial for muscle formation and for myogenic progenitors that migrate from the somite into the developing limb bud. The results also indicated that the myogenin gene is potentially involved in the early stages of muscle determination.
