角质化to change into, or to change so as to contain, keratin (= a strong natural protein, the main substance that forms hair, nails, horns, feathers, etc.)
The skin begins to keratinize quickly. 皮肤很快开始角质化。
In vitamin A deficiency, the cornea keratinizes and becomes opaque. 在维生素A缺乏的情况下，角膜因发生角质化而变浑浊。