Hypodermis: The Fatty Layer
The subcutaneous tissue, or hypodermis, is mostly made up of fat. It lies between the dermis and muscles or bones and contains blood vessels that expand and contract to help keep your body at a constant temperature. The hypodermis also protects your vital inner organs. Reduction of tissue in this layer is what causes your skin to sag.
Sebaceous Glands and Sweat Glands
The sebaceous glands secrete sebum, an oily substance that helps keep skin from drying out. Sebum reduces water loss from the skin surface, protects the skin from infection by bacteria and fungi, and contributes to body odor. These glands are attached to hair follicles.
When your body gets hot or is under stress, sweat glands produce sweat, which evaporates to cool you. Sweat glands are located all over the body but are especially abundant in your palms, soles, forehead, and underarms. The apocrine glands are specialized sweat glands that emit an odor.
Reviewed by doctors at The Cleveland Clinic Department of Dermatology.