Louisiana Esthetics State Board Practice Test

Which layer of skin produces keratin?

1. Basal layer

2. Spiny layer

3. Gradual layer

4. Horny layer

The correct answer is: Gradual layer

The layer of skin that is responsible for producing keratin is the stratum granulosum, which is also referred to as the gradual layer. This layer is located above the spiny layer and below the horny layer in the epidermis. Within the stratum granulosum, keratinocytes begin to undergo a process called keratinization, where they produce keratin, a fibrous protein that helps to form durable and protective properties in the skin. Keratin is essential for providing a barrier against environmental damage, pathogens, and water loss. The presence of keratin increases as the cells move up through the layers of the skin, particularly as they transition from the basal layer, where they are generated, through the spiny layer, and into the gradual layer. In contrast, the basal layer is where new skin cells are generated, the spiny layer provides strength and flexibility due to desmosomes (connections between cells), and the horny layer is primarily composed of dead keratinized cells that form a protective outer layer. While keratin is present in these layers, its production specifically occurs in the gradual layer.