Ontology of Megakaryopoesis.

Abstract SCI-8

Compared to red cells, whose passage from embryonic to adult stages is marked by the expression of distinct forms of hemoglobin, the development of megakaryocytes during embryogenesis is less well understood. However, certain shared characteristics between megakaryocytes, endothelial cells, hematopoietic stem cells and erythrocytes infer developmental relationships between these lineages. Recent data support the model that hematopoietic stem cells derive from the hemangioblast, and that megakaryocytes and erythrocytes develop from a common precursor both in primitive and adult hematopoiesis. Evidence of these common origins can be found in the genetic programs that are activated during hematopoiesis, in that many of the cell surface markers and transcriptions factors that are characteristic of megakaryocytes can also be found in endothelial cells, stem cells and erythrocytes. In this session I will review current views on developmental thrombopoiesis, key megakaryocytic transcription factors and the experimental and clinical phenotypes associated with their disruption, and current controversies in lineage choice during megakaryocyte differentiation.