9.4.1　Rhytidectomy

Collagen fiber is the most abundant component of dermal connective tissue，and its main ingredient is collagen.Collagen in dermis is mainly composed of type Ⅰ collagen（85％-90％），type Ⅱ collagen（8％-11％）and type V collagen（2％-4％）.Elastic fiber plays an important role in maintaining skin elasticity.Elastic fiber is composed of elastin and filiform protein.Elastic fibers and collagen fibers are tangled together to maintain the integrity，strength and elasticity of the skin.After being damaged by external environment and light aging，the structures of collagen and elastin are destroyed，resulting in the decrease of skin elasticity and the generation of wrinkles.

In order to prevent and eliminate wrinkles，there are many ways in the fields of medicine，chemistry and skin beauty，such as physical methods，including laser and bioelectricity.In this section，we will mainly discuss the chemical related anti-wrinkle methods.(https://www.daowen.com)