Final answer:
The formation of new blood vessels important for embryo development and tissue repair is called angiogenesis, a process where angioblasts form vascular structures within the embryo that are crucial for establishing the circulatory system.
Step-by-step explanation:
The correct term for the formation of new blood vessels, which is essential for normal embryo development and tissue repair, is angiogenesis. This process involves the differentiation of precursor cells known as hemangioblasts into angioblasts, which then give rise to blood vessels. As the embryo grows, blood vessels begin to develop from the embryonic mesoderm, forming structures known as blood islands scattered throughout the embryonic disc. Vascular tubes develop and eventually interconnect, helping to establish the embryonic circulatory system. This same process of angiogenesis is also used later in life for tissue growth and repair, and in pathologies such as cancer, where angiogenesis inhibitors can be used to restrict tumor growth by cutting off their blood supply.