Abstract
Studies were made on the absorption of riboflavin by histochemical examination of excised intestine of rat, which was kept in Ringer's solution, containing 5 μg/ml of riboflavin, FMN or FAD at 37℃ for 5 to 20 minutes. Free riboflavin was well absorbed in the isolated intestine. When riboflavin passed through the mucous epithelia, a part of it changed into FMN and the remaining part was absorbed in the form of free riboflavin. FMN was absorbed as well as free riboflavin, and it passed through the mucous epithelia in the form of FMN. FAD was not so much absorbed as riboflavin or FMN.
