Macroscopic examination of homozygous E17.5 Pros^−/− embryos. (A) Most E17.5 Pros^−/− embryos were found dead when harvested, and were severely bruised in the head (left panel), together with localized signs of bleedings and/or thrombosis throughout the body, especially on the back (arrows). (B) E17.5 Pros^−/− embryos did not show any differences in development and gross anatomy with E17.5 Pros^+/− or WT embryos. (C) Extensive intracranial hemorrhages (ICH) and secondary bleedings localized throughout the body (B) were visible in macroscopic histologic analysis of a whole section of E17.5 Pros^−/− embryos.