Macrophages play crucial roles in tissue development and disease. They are involved in processes such as branching morphogenesis, neuronal patterning, angiogenesis, bone morphogenesis, and adipose tissue formation. Their depletion impairs tissue development and function. In diseases like cancer, macrophages can exacerbate pathology by promoting tumor progression and metastasis through mechanisms such as enhancing tumor-cell migration, invasion, and angiogenesis. Macrophages also have trophic roles in development, maintaining tissue integrity and function. Their functions are regulated by growth factors like CSF1 and GM-CSF, and their classification includes M1 and M2 types, though this classification is considered too restrictive. Macrophages are essential for development, as shown by studies in mice with macrophage depletion, which result in severe developmental defects. They are also involved in tissue repair and remodeling, as seen in bone morphogenesis, ductal branching, and neural development. In diseases such as rheumatoid arthritis and atherosclerosis, macrophages contribute to pathology through their trophic and inflammatory functions. Their roles in lipid metabolism and obesity are also significant, with macrophages influencing adipogenesis and insulin resistance. Overall, macrophages are vital for tissue development and homeostasis, and their dysregulation in chronic diseases can lead to severe pathological outcomes. Understanding their functions and regulation is crucial for developing targeted therapies.Macrophages play crucial roles in tissue development and disease. They are involved in processes such as branching morphogenesis, neuronal patterning, angiogenesis, bone morphogenesis, and adipose tissue formation. Their depletion impairs tissue development and function. In diseases like cancer, macrophages can exacerbate pathology by promoting tumor progression and metastasis through mechanisms such as enhancing tumor-cell migration, invasion, and angiogenesis. Macrophages also have trophic roles in development, maintaining tissue integrity and function. Their functions are regulated by growth factors like CSF1 and GM-CSF, and their classification includes M1 and M2 types, though this classification is considered too restrictive. Macrophages are essential for development, as shown by studies in mice with macrophage depletion, which result in severe developmental defects. They are also involved in tissue repair and remodeling, as seen in bone morphogenesis, ductal branching, and neural development. In diseases such as rheumatoid arthritis and atherosclerosis, macrophages contribute to pathology through their trophic and inflammatory functions. Their roles in lipid metabolism and obesity are also significant, with macrophages influencing adipogenesis and insulin resistance. Overall, macrophages are vital for tissue development and homeostasis, and their dysregulation in chronic diseases can lead to severe pathological outcomes. Understanding their functions and regulation is crucial for developing targeted therapies.