Final answer:
The natural moisturizing substances made in the stratum granulosum of the skin are keratin and keratohyalin.
Step-by-step explanation:
The natural moisturizing substances made in the stratum granulosum are keratin and keratohyalin. Keratin is a fibrous protein that makes up a bulk of the keratinocyte mass in the stratum granulosum, while keratohyalin accumulates as lamellar granules within the cells. These substances help give the layer its grainy appearance and play a role in maintaining the barrier function of the skin.