Figure 5.

Dysplasia in the megakaryocytic lineage. Representative images are of (A) Giemsa-stained peripheral blood smears, Giemsa-stained (Bii,C,Di,E,F,Gi,Gii) BM touch preparations, and (Bi,Dii,H) H&E-stained bone sections obtained from wild-type recipients transplanted with Crebbp^+/− LSKs or unfractionated BM cells. (A) Giant platelet (arrow 1) in comparison with normal-sized platelet (arrow 2). (Bi-Bii) Megakaryocytes with eccentric, monolobated nuclei. (C) Binucleated megakaryocyte. (Di-Dii) Multinucleated megakaryocytes. (E) Micro-megakaryocyte (arrow). (F) Megakaryocyte with a ring-shaped nucleus. (Gi) A giant megakaryocyte. The size of this particular one is 10 804.9 μm², in comparison with (Gii) a wild-type megakaryocyte of 1843.7 μm² in size. (H) Emperipolesis of neutrophils (arrow) within megakaryocyte. Magnification: ×60. Scale bars, 10 μm. Of note, bone sections sliced at any particular level merely provide a 2-dimensional representation of the 3-dimensional BM tissue. The appearance of mono/hypolobulation may result from superficial sectioning of a deeper, well-lobulated megakaryocyte. Similarly, what seems to be multiple nuclei may actually represent different lobes of the same nucleus that are connected to each other at a deeper level tissue section. Therefore, although bone sections provide a good approach for preserving the architecture of BM, they can convey a misleading impression of cell morphology, and thus caution needs to be taken when evaluating the nuclear lobes of megakaryocytes. A more accurate evaluation can be made using BM touch preparations where complete cells are attached to the slides.