The Integumentary System: The Dermis

Beneath the epidermis, or top layer of skin, is a thicker, fibrous structure called the dermis, or corium. It consists of the following two layers, which blend together:

• The outer, soft papillary layer contains elastic and reticular (netlike) fibers that project into the epidermis to bring blood and nerve endings closer. Papillae (fingerlike projections) containing loops of capillaries increase the surface area of the dermis and anchor the epidermis. Some of these papillae contain Meissner’s corpuscles, nerve endings that are sensitive to soft touch. It’s the dermal papillae that form the epidermal ridges referred to as fingerprints.

• The inner, thicker reticular layer (from the Latin word rete for “net”) is made up of dense, irregular connective tissue containing interlacing bundles of collagenous and elastic fibers that form the strong, resistant layer used to make leather and suede from animal hides. This layer is what gives skin its strength, extensibility, and elasticity. Within the reticular layer are sebaceous glands (oil glands), sweat glands, fat cells, hair follicles, and larger blood vessels.

  

  Credit: Illustration by Kathryn Born, MA

Cells in the dermis include fibroblasts (from which connective tissue develops), macrophages (which engulf waste and foreign microorganisms), and adipose tissue.

Thickest on the palms of the hands and soles of the feet, the dermis is thinnest over the eyelids, penis, and scrotum. It’s thicker on the back (posterior) than on the stomach (anterior) and thicker on the sides (lateral) than toward the middle of the body (medial). The various skin “accessories” — blood vessels, nerves, glands, and hair follicles — are embedded here.