Final answer:
Oxygen-deprived tissues release erythropoietin (EPO), a hormone that stimulates both red blood cell production and the growth of new capillaries by endothelial cells.
Step-by-step explanation:
Oxygen-deprived tissues secrete erythropoietin (EPO), which signals the endothelial cells to proliferate and grow new capillaries. EPO is a glycoprotein hormone that is secreted by the kidneys in response to low oxygen levels. Its primary role is to trigger the bone marrow to produce more oxygen-carrying red blood cells.
However, in the context of tissue repair and angiogenesis, which is the formation of new blood vessels, EPO can also help to stimulate the healing process by promoting the growth of endothelial cells necessary for new capillary formation.