What makes up 70% of the dermis?

Collagen is the primary structural protein found in the dermis, making up about 70% of this layer of skin. It provides strength, support, and elasticity, playing a crucial role in maintaining the skin's integrity and resilience. Collagen fibers create a framework that enables the skin to withstand mechanical stress and helps in the overall structure of the skin.

In addition to collagen, the dermis contains other components such as elastic fibers, fat cells, and keratinocytes, but these play roles that are secondary to the main structural function of collagen. Elastic fibers contribute to the skin's elasticity, allowing it to stretch and return to its original shape, while fat cells, located in the hypodermis below the dermis, provide insulation and cushioning. Keratinocytes are the primary type of cells found in the outer layer of the skin (epidermis) and are responsible for producing keratin, a protein that protects the skin, but they are not a main component of the dermis itself. Thus, the dominant presence of collagen in the dermis is what makes it the correct choice in this context.