Pennsylvania Esthetician State Board Practice Exam

In which layer of the skin would you find "spiny" irregularly shaped cells?

1. Stratum Lucidum

2. Stratum Granulosum

3. Stratum Spinosum

4. Stratum Corneum

The correct answer is: Stratum Spinosum

The presence of "spiny" irregularly shaped cells is characteristic of the stratum spinosum, which is the layer of the epidermis situated above the stratum basale and below the stratum granulosum. In the stratum spinosum, keratinocytes, which are the primary cells found in the epidermis, are interconnected by desmosomes. These connections create a spiny appearance when viewed under a microscope, giving this layer its name, which translates to "spiny layer." This layer plays a crucial role in the skin's protective barrier and the overall integrity of the epidermis. Moreover, the cells within this layer begin the process of keratinization, where they fill with keratin, preparing to move up to the outer layers of the skin where they eventually die and form the protective outer barrier. In contrast, the stratum lucidum is a thin, translucent layer found only in certain areas of thick skin, the stratum granulosum contains granular keratinocytes that are undergoing further keratinization and have started to lose their nuclei, and the stratum corneum is made up of dead, flattened keratinized cells that provide the most external barrier of the skin. Each of these layers serves distinct