The Link between Oxygen and Basement Membranes.

Epithelial tissues and the basement membranes they sit on did not appear for billions of years. Their appearance was delayed most likely by a lack of oxygen, which is required for collagen synthesis, and which only began to build up following the Great Oxygenation Event ~ 2.4 billion years ago. Both the oxygenation of Earth and the multiple roles of collagen require regulation by electrical forces.