Axial vessels are correctly specified but intersegmental vessels fail to properly sprout and extend in laminin α1 and α4 loss of function embryos. In situ hybridisation of embryos injected with control MO (A, C, E, G) or co-injected with lama1 MO and lama4 MO (B, D, F, H) stained for VE-cadherin (A, B), ephrinB2 (C, D), flt4 (E, F) or VEGF (G, H) expression. In double laminin α1 and α4 loss of function embryos, the dorsal aorta (red arrows) and posterior cardinal vein (blue arrows) properly express markers of endothelial differentiation (A, B) and arterial (C, D) and venous (E, F) identity. The proangiogenic factor VEGF is also comparably expressed in somitic tissue (black arrows) in double morphants (G, H). Multiphoton imaging of trunk vessels in Fli-EGFP transgenic embryos injected with control MO at 24 (I) or 48 hpf (J) or coinjected with lama 1 MO and lama4 MOs at 36(K) or 60 hpf (L). Primary intersegmental sprouts initiate but do not extend and show much less protrusive activity. All panels show lateral views of the mid-trunk region, with anterior to the left, except for panels G and H, which show dorsal views of the mid-trunk region in flat-mounted embryos, with the left side up.
|
