FBS Colloquia No.344Laboratory of Immunology and Cell Biology

The diverse origins of osteoclasts drive bone marrow cavity development through potential cell-cell fusion

Fetal hematopoiesis occurs through “three distinct waves.” The primitive wave generates erythrocytes and macrophages in the yolk sac (YS). The second wave begins with the emergence of hematopoietic stem cells (HSCs) in the aorta-gonad-mesonephros. HSCs then proliferate in the liver, marking the trans-definitive wave. Finally, the definitive wave occurs when HSCs move to the bone marrow to become a source of blood cells. Osteoclast (Oc) plays a crucial role in maintaining the three waves by creating a bone marrow cavity. While Oc originates from either YS or HSCs, the detailed developmental mechanisms and fusion machinery are unknown. This colloquium will introduce the latest research findings, focusing on the mechanisms underlying bone marrow cavity development, particularly emphasizing the potential fusion of osteoclasts.