Fig. 8. Mesodermal expression of Abd-B inhibits muscle formation. (A) MHC accumulation demonstrates aberrations in the formation of skeletal muscles and a complete absence of MHC-expressing cells at the dorsal midline (between arrows). (B-D) Tin accumulation indicates that cardiac defects arise as a result of a loss of tin-expressing cardiac precursors. At stage 13 (B), the tin-expressing population is normal (arrow). By stage 14 (C), many Tin cells are absent. By stage 16 (D), very few Tin-positive cells are detectable in the embryo. (A,D) Dorsal views with anterior towards the left; (B,C) Sagittal views with anterior towards the left. Scale bar: 50 µm.