What is the primary characteristic of the Stratum Granulosum?

The Stratum Granulosum is primarily characterized by its role in creating a waterproof barrier for the skin. This layer is composed of several layers of flattened cells that are rich in keratohyalin granules, which contribute to the formation of keratin and help in establishing this barrier. The granules within the cells of the Stratum Granulosum play a critical role in the process of keratinization, which ultimately aids in preventing water loss from the underlying layers of the skin.

The waterproof aspect is particularly significant because it helps to protect the deeper layers of the skin from external elements and dehydration, maintaining skin hydration and health. The presence of lamellar bodies in this layer further enhances its water-retention properties by releasing lipids that create a barrier.

While other characteristics of the epidermis are noteworthy, such as the thickness of different layers, the presence of dead keratinized cells in other areas, and melanin distribution mainly associated with the Stratum Basale, the defining feature of the Stratum Granulosum is its function in establishing a waterproof layer, which is critical for the overall integrity and function of the skin.