Both systems have highly integrated and extremely complex metabolisms.

Both systems are systemically coupled to other systems, yet demonstrate distinct autonomy.

Both systems control the homeostatic regulation of it's internal environment through homeorhetic circuits.

Both systems display a powerful biological imperative.

Hypoxia stimulates stem cell proliferation in both systems.

Both cellular organizations individuate in a steep positive gradient of oxygen tension.

Both systems have a first trimester exponential growth rate, followed by a slow to ceasing growth rate.