Ever wonder how the complex tangled mess that is our circulatory system could evolve? How do our genes "code" for the miles and miles of convoluted pathways that exist in each our bodies?
The answer is "angiogenesis" and I go into detail on it here.
Blood vessels also undergo natural pruning: https://www.sciencedirect.com/science....
And remodeling: https://www.ahajournals.org/doi/full/...