[Retric]

There are several parts embryo development that does operate on chemical gradients especially the initial stages. But like most of biology it gets really complex and isn’t limited to any one approach.

For example as you gain fat tissue you need to increase the number of capillaries feeding that tissue, which in tern needs to link up to arterioles and arteries on one side and veins on the other. https://www.ncbi.nlm.nih.gov/books/NBK53238/ This happens well into adulthood.