维生素A及其衍生物是上皮组织生长、分化和分泌功能的基本物质。动物缺乏维生素A时,则呼吸道、唾液腺、前列腺等的纤毛上皮或分泌上皮发生鳞状化生(鳞化),给予维生素A时可防止或传递逆转。这种变化其作用机制尚不清楚,在某种意义上可能是一种类似于多肽类的内分泌通过细胞基质发生作用,因为各上皮细胞都具有维生素A结合蛋白的特点,同时在血清中也可分离到这种蛋白。动物实验表 Vitamin A and its derivatives are essential substances for epithelial tissue growth, differentiation and secretion. In the absence of vitamin A in animals, scaly metaplasia (scale formation) occurs in the ciliated epithelium or secretory epithelium of the respiratory tract, salivary gland, prostate, etc., and vitamin A may be prevented or reversed when administered. The mechanism of action of this change is not yet known. In a sense, it may be that a polypeptide-like endocrine acts through the cell matrix, since each epithelial cell has the characteristics of a vitamin A-binding protein and can also be used in serum. The protein was isolated. Animal experiment table