Epithelial cell maintenance (retinoic acid)
Regulation of mucous formation at the level of gene expression, cell differentiation: retina, cornea, lungs, skin, GI tract, etc.
Xerophthalmia“dry eye” (Bitot spots)
Retinoic acid required, especially for mucus formation.
Mucus lubricates the cornea, and its lack allows scratches and bacterial growth in the scratches.
- changes, keratin protein synthesis in follicles