Texas Esthetician License Practice Exam

Which layer of the epidermis is known as the grainy cells?

1. Stratum lucidum

2. Stratum germinativum

3. Stratum granulosum

4. Stratum corneum

The correct answer is: Stratum granulosum

The layer of the epidermis known as the grainy cells is the stratum granulosum. This layer plays a critical role in the skin's barrier function and is characterized by its granular appearance due to the presence of keratohyalin granules. These granules contain proteins that help in the process of keratinization, where skin cells begin to flatten and lose their nuclei as they move toward the surface. In the stratum granulosum, the cells start to lose moisture and become more compact, which is essential for forming a protective barrier against environmental damage and water loss. The process of keratinization is vital for maintaining skin integrity and overall health. The other layers do not exhibit this grainy structure. The stratum lucidum, for instance, is a thin, clear layer primarily found in thicker skin, such as the palms and soles of the feet. The stratum germinativum, also known as the basal layer, is the site of new cell generation and contains living cells that are actively dividing. The stratum corneum is the outermost layer, composed primarily of dead keratinized cells that provide a waterproof barrier but does not have the granular appearance that characterizes the stratum granulosum.