Fig. 5

hand2 promotes vessel progenitor development.

(A–C, F–H, K–M) In situ hybridization depicts etv2 (A–C), tal1 (F–H) and gata1 (K–M) expression in wild-type (A, F, K), han^s6 mutant (B, G, L) and hand2-overexpressing (C, H, M) embryos; dorsal views, anterior to the left, at the 12 somite stage. (A, F) etv2 and tal1 are expressed in relatively medial and lateral (arrows) territories on each side of the wild-type embryo. In han^s6 embryos (B, G), only the medial territory is present. In hand2-overexpressing embryos (C, H), expression of both etv2 and tal1 is increased, but it is not possible to distinguish whether this represents an increase in the medial or the lateral vessel progenitor populations, since no markers exist that distinguish these two groups of progenitors. (K–M) gata1 expression is equivalent in wild-type (K) and han^s6 (L) embryos, but it is decreased in hand2-overexpressing embryos (M). Scale bar represents 100 μm. (D, E, I, J) Fluorescent in situ hybridization depicts the relationship of etv2 and pax2a expression in wild-type (D, D') and hand2 morphant (hand2 MO) embryos (E, E'), and the relationship of tal1 and hand2 expression in wild-type (I, I') and hand2 MO (J, J') embryos; dorsal views, anterior to the left, at the 12 somite stage. Medial and lateral (arrows) territories of etv2 expression flank pax2a in wild-type embryos (D, D'). The lateral territory of expression is absent in hand2 morphants (E, E'). The lateral territory (arrows) of tal1 expression is located at the medial border of hand2 expression in wild-type embryos (I, I'), but is absent in hand2 morphants (J, J'). Note that we observed variable thickness of tal1 expression in its medial territory of expression.