Which of the following statements is (are) true about the stratum basale?
a. The stratum basale contains nerve endings for fine touch.
b. The stratum basale contains more melanocytes in people with dark skin.
c. The stratum basale cells are fully cornified.
d. The stratum basale is a single layer of cells.
e. The stratum basale is present in thick skin but not in thin skin.
The Correct Answer and Explanation is :
The correct answer is D: The stratum basale is a single layer of cells.
Explanation:
The stratum basale (also known as the stratum germinativum) is the deepest layer of the epidermis, which is the outermost layer of the skin. It plays a crucial role in the regeneration of the skin and the formation of new skin cells. Let’s evaluate each of the options to understand why D is the correct answer.
- a. The stratum basale contains nerve endings for fine touch.
- False. While the epidermis does contain sensory nerve endings, the stratum basale itself is not the primary location for nerve endings related to fine touch. The nerve endings for fine touch are primarily found in the stratum papillary layer of the dermis, specifically in specialized structures like Meissner’s corpuscles.
- b. The stratum basale contains more melanocytes in people with dark skin.
- True, but misleading. It is correct that melanocytes, the cells that produce melanin (the pigment responsible for skin color), are found in the stratum basale. However, the number of melanocytes is generally consistent across individuals regardless of skin color. What differs in individuals with darker skin is the activity of melanocytes and the amount of melanin they produce. Thus, while melanocytes are present in all individuals, they are more active in people with darker skin.
- c. The stratum basale cells are fully cornified.
- False. The stratum basale is composed of basal (or stem) cells that are actively dividing and generating new cells. These cells are not yet cornified (hardened and flattened). Cornification occurs as the cells move up through the layers of the epidermis, particularly in the stratum corneum, the outermost layer, where the cells become flattened and filled with keratin.
- d. The stratum basale is a single layer of cells.
- True. The stratum basale is indeed a single layer of cuboidal or columnar cells that sit directly on the basement membrane, which separates the epidermis from the dermis. These cells are responsible for the continuous production of new cells, which then migrate upwards through the other epidermal layers.
- e. The stratum basale is present in thick skin but not in thin skin.
- False. The stratum basale is present in both thick and thin skin. The difference between thick and thin skin is that thick skin has an additional layer, the stratum lucidum, and is typically found in areas subject to more abrasion (like the palms of the hands and soles of the feet). The stratum basale is a fundamental layer in all types of skin.
In conclusion, the stratum basale is a single layer of actively dividing cells, making D the correct statement.