The five distinct layers, or strata, that make up the epidermis, the outer layer of the skin, are crucial for its protective functions. These layers are arranged in a specific order from the deepest to the most superficial.
The skin is composed of two primary layers: the epidermis, which is the outermost layer, and the dermis beneath it. The epidermis itself is a stratified squamous epithelium, meaning it consists of multiple layers of cells, with the deepest layer lying just superficial to the dermis.
Here are the five strata of the epidermis:
| Layer (Stratum) | Alternative Name(s) | Characteristics |
|---|---|---|
| Stratum Basale | Stratum Germinativum | The deepest layer, lying just superficial to the dermis. It contains continuously dividing cells that replenish the more superficial layers. |
| Stratum Spinosum | Prickle Cell Layer | A relatively thick layer characterized by keratinocytes that appear "spiny" due to desmosomal junctions. |
| Stratum Granulosum | Contains keratinocytes that are undergoing a process of keratinization, forming granules within their cytoplasm. | |
| Stratum Lucidum | A thin, clear layer found only in thick skin (like the palms of hands and soles of feet), appearing translucent. | |
| Stratum Corneum | The outermost and thickest layer, composed of flattened, dead keratinocytes filled with keratin, providing a tough, protective barrier. |
Each layer plays a vital role in the overall integrity and function of the skin, from cell production and maturation to providing a robust barrier against environmental stressors and preventing water loss.
