Comparison of the expression patterns of seven genes involved in hematopoiesis and vasculogenesis in wild-type embryos and embryos homozygous for one of two different mutations. Whole-mount in situ hybridization of 24-h-old wild-type (A–G), spadetail (sptb104) (H–N), and cloche (clom39) (O–U) embryos with lmo2 (A, H, O), gata2 (B, I, P), c-myb (C, J, Q), gata1 (D, K, R), fli1 (E, L, S), flk1 (F, M, T), and flt4 (G, N). Arrowhead in A indicates trunk lmo2 expression. In spt mutant embryos, cells expressing lmo2 (H) and gata2 (I) are found in the morphologically distorted ICM region and tails. However, very few if any hematopoietic cells expressing gata1 (K) or c-myb (J) are seen in these embryos. The expression levels of the vascular markers fli1 (L), flk1 (M), and flt4 (N) appear normal in these embryos; however, the patterns are distorted by the abnormal somites. In clo mutant embryos, ICM cells and tail cells that express lmo2 (O) or gata2 (P) are not found. While the expression of fli1 (S), gata1 (R), c-myb (Q), flk1 (T), and flt4 (U) is missing in the anterior ICM of clo mutant embryos, a small number of posterior ICM and tail cells continue to express these markers (arrows in O–U). The expression of c-myb in the eye, gut, and skin-associated cells appears normal in all of these mutants (C, J, Q).