Final answer:
The Stratum granulosum mainly contains keratinocytes, which produce keratin and keratohyalin, making up most of the keratinocyte mass and giving this skin layer its characteristic grainy appearance.
Step-by-step explanation:
The primary type of cells found in the Stratum granulosum are keratinocytes that are undergoing changes that give this layer a grainy appearance. These changes include the cells becoming flatter and their cell membranes thickening. Within these cells, large amounts of the proteins keratin and keratohyalin are generated, with keratohyalin accumulating as lamellar granules. Consequently, the keratinocyte mass in the Stratum granulosum is comprised mainly of these two proteins. As the cells move away from the source of nutrients and oxygen, their nuclei and other organelles disintegrate, and the cells die. The remaining keratin, keratohyalin, and thickened cell membranes form the basis of the following superficial layers such as the stratum lucidum and the stratum corneum, and also contribute to hair and nail formation.
The main type of cells found in the stratum granulosum are called keratinocytes. Keratinocytes are responsible for producing the proteins keratin and keratohyalin, which give the layer its grainy appearance. These proteins accumulate as lamellar granules within the cells. As the keratinocytes in the stratum granulosum die, they leave behind the keratin, keratohyalin, and cell membranes that will form the stratum lucidum, the stratum corneum, and the accessory structures of hair and nails.