近二十多年来,许多生物学家在大量实验中得知,维生素甲类具有一种独特的潜能,能控制和调节动物上皮组织的分化。由于它的减少和缺乏,引起柱状上皮组织的改变,粘液细胞数量减少;并出现鳞状化生。相反,超量维甲类则引起角化上皮组织发生改变,出现典型杯状粘液 For nearly two decades, many biologists have learned in a large number of experiments that vitamin A has a unique potential to control and regulate the differentiation of animal epithelial tissues. Due to its reduction and lack of, causing changes in the columnar epithelium, mucus cells reduce the number; and the emergence of squamous metaplasia. In contrast, excessive retinoids cause keratinized epithelial tissue to change, with typical goblet mucus