Number of megakaryocytes. (A) Comparison of the number of megakaryocytes in bone marrow and spleen of WT (n = 3) and Mx1-C1 (n = 3) mice. Values are expressed as means ± standard error (SE) relative to the WT level (100%). *P < .01. (B) Photomicrograph of a hematoxylin and eosin–stained bone marrow section illustrating a megakaryocyte intimately associated with marrow vessels. Scale bar, 10 μm. (C) Quantification of megakaryocyte number associated with sinusoidal vessels in WT (n = 3) and Mx1-C1 (n = 3) mice. Values are presented as means ± standard error of the mean (SEM).