Vascular defects in Reck -deficient mice. (A) Schematic representation of the 5'-terminal region of the wild type (wt) and a Reck mutant (Reck-) allele. This mutant allele lacks exon 1 and hence no Reck protein is expressed . (B) A typical E10.5 wild type embryo (panel 1) and a Reck-/- embryo (panel 2) which shows abdominal hemorrhage and dilated vessels (panel 3, magnified view of the area indicated by yellow box in panel 2). The heart was beating in this typical mutant embryo. (C) The perineural area in the sagittal sections of wild type (panel 1) or Reck-/- (panel 2-4) embryos stained for a basement membrane-marker, laminin. The samples in panels 2-4 represent mild, intermediate, and severe phenotypes, respectively. The blue arrows in panel 1 indicate contact zones in the wild type perineural vascular plexus, the green arrows continuous perineural vessels (panels 2, 4), and the red arrows winding vascular spaces or tissue slits (panels 3, 4). (D) Vascular networks in E10.5 wild type (panel 1; a magnified view in panel 2) or Reck-/- (panel 3, a magnified view in panel 4) yolk sac visualized by whole-mount immunostaining for Flk-1. Blue arrows and red arrows indicate small holes and abnormal sprouts, respectively. Scale bar: B, 1 mm in panels 1, 2 and 200 μm in panel 3; C, 50 μm; D, 20 μm in panels 1, 3 and 10 μm in panels 2, 4.