the process in which cytoplasm (= the substance surrounding a cell nucleus) in the top layer of skin cells changes into, or changes so as to contain, keratin (= a strong natural protein, the main substance that forms hair, nails, horns, feathers, etc.)

Keratinization is the acquisition of a horn-like character by the epithelial tissue in many parts of the body. 角质化是指身体许多部分的上皮细胞获得了类似犄角的特征。

Acne may be a manifestation of a keratinization disorder. 粉刺可能是角质化紊乱的一种表现。