What is the most common connective tissue fiber found in the dermis?

The most common connective tissue fiber found in the dermis is collagen fiber.

Explanation:

The skin is the integument that covers and protects the body of human beings and animals. The skin consists of three layers: Epidermis, the outermost layer of skin; the dermis is located beneath the epidermis and the hypodermis is the innermost layer of the skin.

The dermis is the support structure of the skin and provides resistance and elasticity. This is basically formed of dense connective tissue, which has a high proportion of densely packed collagen fibers, with poorly active fibroblasts. The extracellular matrix contains a high proportion of fibers, not very compacted, mostly collagen fibers (around 75%), also contains elastin and reticulin. Fibroblasts synthesize and release the precursos of collagen, elastin and proteoglycans to build the extracellular matrix.

The dermis consists of two well-defined regions: papillary and reticular layer.

The papillary dermis, of loose connective tissue, is arranged forming protrusions called dermal papillae that determine a ripple in the epidermis. In this layer the collagen fibers are thin and are arranged parallel to the surface.

The reticular dermis is the thickest and is located below the papillary, where the collagen fibers interwave with other fibrous bundles (elastic and reticular) forming a network; this layer represents the true fibrous bed of the dermis. Collagen fibers show a direction parallel to the skin surface and form tension lines.