Ly-6C, also known as lymphocyte antigen 6 complex, is a cell surface glycoprotein that is widely used to identify functionally distinct murine circulating monocyte populations. It plays a critical role in the immune system, particularly in the activation and regulation of macrophages and monocytes. Ly-6C is expressed on various cells, including macrophages, dendritic cell precursors, granulocytes, and subsets of B- and T-lymphocytes. It is often used as a marker to differentiate between classical monocytes (Ly-6Chi) and non-classical monocytes (Ly-6Clo). In the context of tissue repair and fibrosis, Ly-6C expression has been shown to be important for identifying macrophage subsets that mediate tissue remodeling. Moreover, Ly-6C has been used as a marker for studying vascular changes in health and disease. It has been shown to be a useful marker for visualizing the retinal vasculature in mice, and its expression can be used to assess vascular changes in response to injury such as retinal ischemia.