Final answer:
The stratum granulosum is the sublayer of the epidermis featuring granular-looking keratinocytes, which start to die as their nuclei disappear, contributing to the formation of the skin's upper layers.
Step-by-step explanation:
The sublayer of the epidermis characterized by the appearance of granules and the disappearance of the nucleus within the cells is known as the stratum granulosum. This layer exhibits a grainy appearance due to changes in the keratinocytes, which are flat, dying cells that have thickened cell membranes and are packed with large amounts of proteins, particularly keratin and keratohyalin. These proteins accumulate as lamellar granules within the cells, contributing to the granular appearance.
s keratinocytes move away from the nutrient-rich blood vessels of the dermis and ascend through the layers of the epidermis, they lose their nuclei and other cell organelles, eventually resulting in cell death. The remnants of these cells then contribute to the formation of the successive layers of the epidermis and the accessory structures such as hair and nails.