Transient GFP expression generated using the ∼2.2-kb col10a1:GFP construct in developing zebrafish embryos. (A–D) A bright field image and an image showing GFP expression are shown as a pair for embryos at each stage. The ∼2.2-kb col10a1 promoter induces GFP expression in the cl at 2 dpf (A, A′); in the cl and op at 3 dpf (B, B′); and in the cl, op, br, and cb5 at 4 dpf (C-D′). This expression pattern was maintained until the zebrafish was at least 1 month old (E). Ectopic GFP expression, for example, in the pectoral fins, was detected in some embryos (E′). cl, cleithrum; op, opercle; br, branchiostegal ray; cb5, ceratobranchial 5; pf, pectoral fin.