Immunohistochemical analysis of cortactin expression in megakaryocytes. Mature megakaryocytes stain positively in bone marrow, spleen, and liver. Platelets that cover the de-endothelialized intima (arrow) stain positively as well. (A) Bone marrow (original magnification × 160); (B) spleen (original magnification × 20); (C) liver of a mouse embryo (12.5 days, original magnification × 30); (D) a balloon-injured rat carotid artery (original magnification × 120) 24 hours after injury.