The hormones that control the menstrual cycle are estrogen and progesterone. The two backbones of DNA are adenine and thymine. The three layers of human skin are the epidermis, dermis, and subcutaneous layer. The epidermis is the outermost layer and is responsible for providing a waterproof barrier and producing new skin cells. The dermis is the middle layer and is responsible for providing strength and elasticity to the skin. The subcutaneous layer is the innermost layer and is responsible for providing insulation and cushioning.
