Histology of spleen and bone marrow. A1 and A2, Lymphoid hypoplasia is visible in the splenic white pulp. B1 and B2, Bone marrows tissue shows replacement of red hematopoietic bone marrow with yellow adipocyte-rich marrow. Megakaryocyte hyperplasia is observed (arrows). Abbreviation: H&E, haematoxylin and eosin. C1, Macrophages (CD68+) are present in bone marrow tissue. C2, CD68+ cells displaying features of hemophagocytosis (arrow). Scale bars: A1, A2, B2–C2, 7 µm; B1, 100 µm.