Which epidermal layer is known as the granular layer and contains cells filled with keratin that resemble granules?

Which epidermal layer is known as the granular layer and contains cells filled with keratin that resemble granules?

• A. Stratum granulosum
• B. Stratum corneum
• C. Stratum spinosum
• D. Stratum basale

Answer: (A)

The granular layer is the part of the epidermis where keratinocytes are finishing their maturation. This layer contains keratohyalin granules, which give a granular appearance and help drive the final steps of keratinization by promoting keratin formation and cell flattening. As cells move from the spinous layer into the granular layer, they become more flattened, lose their nuclei and organelles, and release lipids that create a waterproof barrier before the cells reach the outermost, dead layer. This is why the granular layer is the best choice: it’s defined by those keratin-filled granules and by its role in beginning keratinization and forming the barrier. The outermost layer consists of dead, keratin-filled cells without granules; the spinous layer is still living and formative, and the deepest layer is the basale where cells actively divide.

The granular layer is the part of the epidermis where keratinocytes are finishing their maturation. This layer contains keratohyalin granules, which give a granular appearance and help drive the final steps of keratinization by promoting keratin formation and cell flattening. As cells move from the spinous layer into the granular layer, they become more flattened, lose their nuclei and organelles, and release lipids that create a waterproof barrier before the cells reach the outermost, dead layer.

This is why the granular layer is the best choice: it’s defined by those keratin-filled granules and by its role in beginning keratinization and forming the barrier. The outermost layer consists of dead, keratin-filled cells without granules; the spinous layer is still living and formative, and the deepest layer is the basale where cells actively divide.