Ectodermal cells in the pectoral fins express the eng1 gene. Parasagittal sections through the distal portion of the pectoral fin buds of 32 h embryos were hybridized with probes for the engt (top) , eng2(middle) or eng3 (bottom) genes. The lateral ectoderm in the ventral part of the bud (arrows) hybridized with only the eng1 probe. The red signals in the lower part of Band C are due to the yolk, rather than specific hybridization, as shown in unhybridized control sections. Scale bar, 50 μm.