colXIX RNA is dynamically expressed during motor axon outgrowth. (A-D′) RNA in situ hybridization using colXIX anti-sense (A-D) and sense (A2-D′) riboprobes that encompasses exons 1-27 of the zebrafish colXIX cDNA at (A,A′) 19 hpf, (B,B′) 24 hpf, (C,C′) 30 hpf and (D,D′) 36 hpf. Sections were from the mid-trunk region. (E) Histogram of colXIX RNA in situ hybridization intensity at 19 hpf for wild-type (n=8 embryos; -40 sections) and stumpy mutant embryos (n=8 embryos; -40 sections). The x-axis reflects the intensity of the colXIX expression. Spinal cord (sc) and notochord (nc) are indicated by white borders. Arrows show localization of colXIX transcripts in the myotome. Scale bar: 20 μm.