Fig. 1. Axial or lateral structures do not affect the epithelial structure of the dermomyotome. (A) Schematic of the experiment: separation of the anterior PSM from axial structures (neural tube and notochord) by making a slit through the three germ layers of the embryo. Embryos were then cultured for 18-20 hours. (B) Scheme of the separation of PSM from lateral structures. (C,D) Transverse sections of embryos in E and G. (E,F) Expression of Fz7 and paraxis is maintained after separation of the PSM from axial structures. The residual expression of paraxis and Fz7 along the neural tube is due to remnants of somitic tissue and ectoderm that have not been completely separated from the neural tube (and confirmed on sections, not shown). (G) Expression of Fz7 is not affected after separation of the PSM from lateral structures.