Table 1.
Anatomical feature | Cellular components | Molecular components | Function | ||
---|---|---|---|---|---|
Epidermis | |||||
Stratum Corneum | A cornified layer possessing a “bricks and mortar” structure | Corneocytes, the dead cells lacking nuclei and organelles | Intercellular lamellar lipid bilayers | Contributes significantly to the permeation barrier properties of skin | |
Stratum Lucidum | A thin and clear/translucent layer found only in certain areas of thick skin | The major cells of the viable epidermis are keratinocytes (90–95%). As the keratinocytes in the basal layer of epidermis proliferate, the daughter cells migrate superficially and differentiate, forming the shallower layers | Flattered and dead keratinocytes filled with eleiden, an intermediate form of keratin | Oily lamellar bodies containing lipids and proteins | Water proof barrier preventing fluid loss |
Stratum Granulosum | A highly differentiated granular layer | Keratinocytes becoming granular cells that contain keratohyalin granules | |||
Stratum Spinosum | A spinous layer where keratinization begins | Adjacent keratinocytes are joined together by desmosomes; Langerhans cells (the dendritic cells) |
Cytokeratins, the intermediate filaments of keratin, and desmosomes | Cytokeratin-desmosome networks provide structural support, helping the skin resist abrasion. Langerhans cells contribute to the immunological response of the skin |
|
Stratum Basale | The deepest layer of epidermis | Melanocytes produce melanin that contributes to skin pigmentation and protects the skin from harmful ultraviolet radiation; Merkel-Ranvier cells (the oval receptor cells) contribute to sensory reception). | This is where the epidermal (keratinocytes) differentiation initiates | ||
Dermis | |||||
Papillary Dermis | A layer intertwined with the overlaying epidermis, forming rete pegs and rete ridges along the dermal-epidermal junction | Fibroblasts, macrophages, and adipocytes | Collagen, elastin, glycos-aminoglycans and glycoproteins | Provides tight contact between epidermis and dermis | |
Reticular Dermis | A layer of dense collagen and elastic fiber matrix | Main source of the strength, flexibility and elasticity of the skin. |