Which epidermal layer contains stem cells? ? Stratum lucidum ? Stratum corneum ? Stratum granulosum ? Stratum basale
The correct answer and explanation is:
Correct Answer: Stratum basale
Explanation (300 Words):
The stratum basale (also known as the basal layer or stratum germinativum) is the deepest layer of the epidermis and is the only layer that contains stem cells capable of continuous division. These epidermal stem cells are essential for the regeneration and repair of the skin. They divide to form new keratinocytes, which are the primary cell type in the epidermis.
Once formed in the stratum basale, keratinocytes gradually migrate upward through the layers of the epidermis, undergoing differentiation as they move. During this journey, they begin producing keratin, a structural protein that helps form the protective barrier of the skin.
Here is a brief overview of each layer for context:
- Stratum basale: Bottommost layer. Contains stem cells, melanocytes (produce pigment), and Merkel cells (involved in touch sensation).
- Stratum spinosum: Above the basal layer. Cells start producing more keratin and begin to interconnect.
- Stratum granulosum: Cells begin to die and become more keratinized, forming a barrier to water.
- Stratum lucidum: Found only in thick skin (like palms and soles). A thin, translucent layer of dead cells.
- Stratum corneum: Outermost layer. Fully keratinized, dead skin cells that are continuously shed.
The stratum basale is crucial because, without its stem cells, the skin would not be able to heal wounds or regenerate after injury. It plays a key role in both normal skin maintenance and in conditions like skin cancer (e.g., basal cell carcinoma, which arises from cells in this layer).
In summary, the stratum basale is the only layer of the epidermis that contains stem cells, making it essential for skin growth and repair.