Thrombopoietin (TPO) is a glycoprotein hormone that plays a critical role in the regulation of platelet production and megakaryopoiesis, the process by which megakaryocytes give rise to platelets. TPO acts on hematopoietic stem cells and progenitor cells in the bone marrow, stimulating their differentiation into megakaryocytes and promoting platelet formation. TPO exerts its effects by binding to the c-Mpl receptor on the surface of hematopoietic cells, leading to the activation of signaling pathways that regulate cell proliferation, survival, and differentiation. Dysregulation of TPO signaling has been implicated in various hematological disorders, such as thrombocytopenia and myeloproliferative neoplasms.