Endothelial development is severely disrupted in Lmo2-depleted embryos. (A-B) Whole-mount 10s embryos; views as indicated; dorsal, top. (C-L) Whole-mount embryos; lateral view; close-up of trunk/tail region; anterior, left. Numbers of embryos represented in gray. (A-B) At 10s, flk1 and flt4 expression in the ALM and PLM was substantially reduced in morphant embryos. (C) In 24-hpf morphants, fli1 expression was reduced in the trunk region and sprouting of primary ISVs was mostly absent (arrows). (D-E) Tie1 and flk1 expression was significantly reduced in the trunk in 22-hpf morphants. (F-G) However, flt4 and tie2 expression at 24hpf was not as significantly down-regulated in morphant embryos. (H-J; arrows) Expression of ephrinB2a (H) deltaC (I), and notch5 (J) in the DA was lost in 22-hpf morphants. (K-L; arrows) Although expression of the vein-specific marker ephB4 (K) was not down-regulated, msr expression in the PCV was lost (L).