Fig. 6. Reconstructions of stage 29-30 (6-6.5 day) embryos showing the distribution and differentiation of cells derived from mesoderm transplants. A shows an enlargement of the LR and adjacent structures. All grafts contribute to the LR and the pyramidalis muscles, and usually to proximal first arch muscles, especially the palpebral depressor primordium. Many embryos also exhibited labeling in the DO. In contrast to control grafts (A), all trunk-into-head grafts (B-E) produce a large number of ectopic muscles. These are not randomly distributed, but form in large irregular aggregates beside the isthmus, and as small clusters and single myotobes dispersed in a supra-orbital band deep to and paralleling the dorsal margin of the eye.