The bone marrow niche for hematopoietic stem cells (HSCs) is a local tissue microenvironment that maintains and regulates HSCs. The niche is perivascular, created by mesenchymal stromal cells and endothelial cells, often located near trabecular bone. Key components include CXCL12-expressing perivascular stromal cells and endothelial cells, which synthesize factors like SCF and CXCL12 that promote HSC maintenance. Osteoblasts and osteolineage cells also play a role, though their direct effects on HSCs are less clear. The niche is complex, with multiple cell types contributing to its function, and its composition and function can vary under different physiological conditions or in response to stress. Understanding the bone marrow niche is crucial for improving regeneration following injury or HSC transplantation and for elucidating how disordered niche function may contribute to diseases.The bone marrow niche for hematopoietic stem cells (HSCs) is a local tissue microenvironment that maintains and regulates HSCs. The niche is perivascular, created by mesenchymal stromal cells and endothelial cells, often located near trabecular bone. Key components include CXCL12-expressing perivascular stromal cells and endothelial cells, which synthesize factors like SCF and CXCL12 that promote HSC maintenance. Osteoblasts and osteolineage cells also play a role, though their direct effects on HSCs are less clear. The niche is complex, with multiple cell types contributing to its function, and its composition and function can vary under different physiological conditions or in response to stress. Understanding the bone marrow niche is crucial for improving regeneration following injury or HSC transplantation and for elucidating how disordered niche function may contribute to diseases.