Increased megakaryopoiesis in Tc1 mice older than 15 months. (A) Photomicrographs of sections of spleens from a Tc1 mouse with an enlarged spleen and a wild-type (Wt) control mouse, both aged 15 months. Sections were stained with hematoxylin and eosin, or with antibodies to CD41 or Ter119. The enlarged Tc1 spleen shows an increased number of megakaryocytes seen both in the hematoxylin and eosin and anti-CD41 stains. (B) Bone marrow sections from Wt and Tc1 mice stained as in panel A. Scale bars in panels A and B indicate 100 μm.