Expression of bmp4 in wt (A, C) and Ztmem2 mutant (B, D) embryos at 48 hpf, as in Fig. 2. Pericardial injection of PBS did not alter the bmp4 expression pattern in wt (A) or Ztmem2 mutant (B) embryos (compare to Fig. 2A,B). In contrast, pericardial injection of hyaluronidase restored the concentrated expression of bmp4 at the AVC in the majority of the injected Ztmem2 mutants (D, arrowheads; Table 3), but did not affect the bmp4 expression pattern in the majority of the injected wt sibling embryos (C, arrowheads; Table 3).