Mouse Thrombopoietin (TPO) (also known as THPO or megakaryocyte growth and development factor, MGDF) is a hematopoietic cytokine that plays a central role in the regulation of platelet production and megakaryocyte development in mice (Mus musculus). TPO belongs to the class I cytokine family, which also includes erythropoietin (EPO), granulocyte colony-stimulating factor (G-CSF), and prolactin, cytokines that regulate blood cell development through related receptor-mediated signaling pathways. In mice, TPO is produced primarily by the liver, with additional expression in the kidney, bone marrow stromal cells, and other tissues, and it exerts its biological effects by binding to the c-Mpl receptor (MPL, CD110) expressed on hematopoietic stem cells and megakaryocyte progenitor cells. Activation of the TPO receptor stimulates intracellular signaling pathways including JAK2/STAT, MAPK, and PI3K/AKT, promoting megakaryocyte proliferation, maturation, and platelet formation while also supporting hematopoietic stem cell survival and self-renewal. Mouse TPO has been extensively studied using genetic knockout and transgenic models, which demonstrate that disruption of the TPO–MPL signaling axis leads to severe thrombocytopenia and impaired hematopoietic stem cell maintenance. Because mice are widely used as experimental models for hematology and stem cell biology, characterization of mouse thrombopoietin has been critical for understanding platelet production, bone marrow regulation, and hematopoietic stem cell homeostasis, providing insights relevant to human blood disorders and therapeutic development.