I know that there are two usual ways of creating new blood vessels:
- A new vessel sprouts from the wall of an old one,
- A wall of cells grows down the middle of a vessel, splitting it into two.
I also know that capillaries are all the same size (about wide enough for a single red blood cell to get through). I also know that in between the major blood vessels and the capillaries, you have a hierarchical branching of differently sized tubes.
So my question is to do with, like. So if a new blood vessel starts to sprout, does it start off as wide at the base, as it's always going to be? (E.g. does it already know how many times it'll have to branch before getting to the capillaries, and choose its width accordingly?) Or does it start off smaller, but widen at the base as its ends keep branching?