Oregon Esthetician State Board

What is the third layer of the epidermis?

1. Stratum germinativum

2. Stratum lucidum

3. Stratum corneum

4. Stratum granulosum

The correct answer is: Stratum granulosum

The third layer of the epidermis is the stratum granulosum. This layer is located above the stratum spinosum and beneath the stratum lucidum (in thick skin) or the stratum corneum (in thin skin). The stratum granulosum is characterized by the presence of keratinocytes that begin the process of keratinization, where they accumulate keratohyalin granules. These granules play a crucial role in the formation of the skin's protective barrier, as they contribute to the waterproof properties of the skin. This layer helps in the transition of cells from living to dead, aiding the process of exfoliation. The other layers mentioned don’t correspond to the third layer in the epidermis. The stratum germinativum, or basal layer, is the deepest layer responsible for generating new skin cells. The stratum lucidum is typically found only in thicker skin areas, such as the palms of the hands and soles of the feet, and serves as an additional barrier. Lastly, the stratum corneum is the outermost layer, providing the main barrier against environmental hazards. Understanding the specific roles and characteristics of each layer is essential for both estheticians and individuals studying skin anatomy