Glomeruloid bodies had fibrin deposition and endothelial cell disarray. (A) Sagittal sections of E15.5 littermate brains stained with anti-fibrin(ogen). The inset of the Tfpi^−/− brain shows fibrin(ogen) deposits inside and outside the vascular compartment, suggesting vasculature leakage around the glomeruloid bodies (arrows). Areas of cell death characterized by pyknotic nuclei were adjacent to the glomeruloid bodies (arrowheads). Fibrin(ogen) deposition was not observed in the Tfpi^+/+ brain (scale bars, 100 µm [inset, 30 µm]). (B) Sagittal sections of E15.5 littermate brains stained with an anti-laminin antibody. Numerous glomeruloid bodies throughout multiple areas of the Tfpi^−/− brain were outlined by laminin staining of the basement membrane. Glomeruloid bodies were not present in Tfpi^+/+ brain (scale bars, 100 µm [inset, 30 µm]). (C) Immunofluorescence of littermate brains stained for laminin (red/yellow) and thrombomodulin (THBD; green), with 4′,6-diamidino-2-phenylindole (DAPI)–stained nuclei (blue). Tfpi^+/+ brain had well-organized vasculature with thrombomodulin-stained endothelial cells internal to the laminin-stained vascular basement membrane. Tfpi^−/− embryo brain had disorganized multilobular vasculature containing thrombomodulin-stained endothelial cells in disarray surrounded by a laminin-stained basement membrane (scale bars, 10 µm).