FIGURE 2.

Gata1^low megakaryocytes remain immature and the nuclei of some of them present a tightly condensed chromatin characteristic of para-apoptosis, an immune-mediated form of cell death probably induced by pathological neutrophil emperipolesis. (a) Electron microscopy analyses of a mature wild-type megakaryocyte with properly developed demarcation membrane system and delineated platelet territories. (b) Electron microscopy analyses of one representative immature (left panel) and one representative para-apoptotic (right panel) Gata1^low megakaryocyte. (c) Electron microscopy analyses of a representative mature megakaryocyte from a Gata1^low mouse treated with the TGF-β inhibitor SB431542. Magnification ×4,400. Similar results were published in References 31 and 45