What function does the stratum granulosum serve?

The stratum granulosum serves an essential function in the epidermis by contributing to the process of keratinization, which involves the formation of a protective barrier on the skin. Within this layer, cells begin to lose their nuclei and other organelles, undergoing a form of programmed cell death known as apoptosis. This process is crucial because it allows the cells to eventually become more flattened and filled with keratin and other proteins, transforming into the tough, protective cells of the outermost layer of the skin, or stratum corneum.

By facilitating the transition from living cells to keratinized cells that help form a strong barrier, the stratum granulosum plays a vital role in skin health and homeostasis. Although the other options mention various functions that relate to skin health—like protection against bacteria and moisture—these processes are more directly associated with other layers of the epidermis or overall skin function rather than the specific role of the stratum granulosum in cell apoptosis and keratinocyte maturation.