Michigan Esthetician State Board Practice Exam

In which layer of the skin does cell division primarily occur?

1. Stratum corneum

2. Stratum granulosum

3. Stratum germinativum

4. Stratum lucidum

The correct answer is: Stratum germinativum

Cell division primarily occurs in the stratum germinativum, also known as the basal layer of the epidermis. This layer is composed of living cells that are actively undergoing mitosis, a process where cells divide to create new cells. These newly formed cells gradually migrate upwards through the layers of the epidermis as they mature and differentiate. The stratum corneum is the outermost layer of the skin, consisting mainly of dead, flattened keratinocytes that have undergone a process called keratinization. This layer serves primarily as a protective barrier, and since the cells are no longer alive, there is no cell division occurring here. The stratum granulosum contains keratinocytes that are transitioning to a more mature state, starting to lose their cytoplasmic organelles and filling with keratin. While some changes to the cells occur here, it does not primarily serve as the site of active cell division. The stratum lucidum is a thin, clear layer found only in areas of thick skin, such as the palms and soles of the feet. This layer acts as an additional barrier and does not contain living cells that are dividing. Thus, the primary activity of cell division occurs in the stratum germinativum, making it