Immunohistochemical detection of activated caspase-3 in megakaryocytes from a healthy donor, and MDS and ITP patients. (A) A bone marrow biopsy from an ITP patient showing a caspase-3 immunopositive megakaryocyte. (B) Bone marrow of a healthy donor has been immunostained in the same way. Note that the megakaryocytes are free of caspase-3 reactivity. (C) A bone marrow sample of an MDS patient showing megakaryocytes (indicated by arrowheads) that are negative for activated caspase-3. Small arrows indicate caspase-3 immunopositive labeling in normoblasts. Magnification × 400. Slides were observed with an Olympus BX50 microscope (Paes Nederland, Zoeterwoude, The Netherlands) using a 40×/0.75 numerical objective lens. Images were captured with an Olympus DP70 camera (Paes Nederland) and image analysis software (SIS, Münster, Germany). Images were further processed using Adobe Photoshop CS and Illustrator CS (Adobe).