Effects of c-mpl ablation on megakaryocytic NR1 expression. Immunohistochemical identification of NR1 expression by bone marrow megakaryocytes (arrows) from wild-type control mice (c-mpl^+/+; panel A) and c-mpl knock-out mice (c-mpl^–/–; panel B). (C) Antibodynegative control. DAB-peroxidase disclosure with hematoxylin counterstain. Arrows refer to the position of megakaryocytes.