The biology of myelopoiesis

The myelopoietic system includes the hematopoietic cells derived from a common hematopoietic stem cell that includes erythroid, granulocytic, monocytic, and megakaryocytic lineages. The contributions of molecular genetic techniques to hematopoiesis in the past 5 years have led to quantum leaps in our understanding, but there is room for further research. Current concepts of stem cells and the hematopoietic microenvironment are discussed, as are committed progenitor cells and hematopoietic growth factors, particularly those concerning the neutrophilic, monocytic, and erythroid systems.