Image: rat skin. It is a region of the hand skin with a thickness of the epidermis between the palm (very thick) and dorsal region of the hand (thin epidermis). Staining: hematoxylin and eosin in paraffin section.
Epidermis: epithelial layer mostly consisting of keratinocytes. Several layers can be distinguished in the epidermis: stratum basale, stratum spinosum, stratum granulosum and stratum corneum.
Stratum corneum: the outermost layer of the epidermis. It is made up of dead keratinocytes. Keratinocytes are continuously detached from the stratum corneum. This layer protects against mechanical insults and water loss.
Dermis: layer of connective tissue found immediately below the epidermis. Epidermis and dermis, together with hypodermis, form the skin. The dermis is dense irregular connective tissue, and the density of the its extracellular matrix depends on the intensity of the mechanical stress.
Hypodermis: layer of tissue found below the dermis. It is made up of loose connective tissue and many adipose cells (adipocytes). The thickness of the hypodermis is variable and depdens on the region of the body.
Adipocytes: cells specialized in storing lipids. Although adipocytes look empty in the image, they are actually filled with a very large lipid droplet.
Hair follicle: they are invaginations of the epidermis of mammals, where the hair is produced.
Sebaceous gland: they are exocrine glands that release their content into the hair follicle channel, from which the released molecules reach the skin surface. These substances are altogether called sebum.