Massachusetts State Board Esthetics Practice Exam

The layer of the epidermis that is filled with keratin granules is the stratum granulosum. This layer is critical in the process of keratinization, where the cells develop a high concentration of keratohyalin granules that contribute to the formation of keratin. This transformation helps create a waterproof barrier, essential for protecting the underlying tissues from dehydration and external pathogens. In this layer, keratinocytes begin to lose their nuclei and cytoplasmic organelles as they move upward towards the surface. The keratin granules present in the stratum granulosum also play a role in the skin's barrier function, and as these cells die and lose their moisture, they become flattened and form the protective outer layer of the skin. This essential function is part of the natural aging process of skin cells, contributing to the overall health and resilience of the skin.