T cells are absent in mutant line 116 embryos. (A,B) WISH showing that early T cell markers (rag1, rag2 and bcl11b), HSPC markers (cmyb and ikaros) and T cell markers (ccr9a, ccr9b, tcrb2 and tcrd) are absent in the thymus of mutant line 116 at 5dpf. By contrast, thymus epithelial cell marker foxn1 was normal in the thymus of 116 mutants at 5dpf. Red arrowheads indicate the thymus. Numbers at bottom right indicate the number of embryos with similar staining pattern among all embryos examined.