Histochemical study on orotic acid.

Recently orotic acid has been noticed as a growth factor and regarded as a pre cursor of nucleic acid (1, 2). But its distribution in organisms has scarcely been studied except for tracing the acid using C14-labeled compound (3). The authors have found that orotic acid shows a whitish blue primary fluorescence, which is re markably intensified by adding H2O2. Applying this property to histochemistry, the authors have succeeded in observing the histological distribution of orotic acid in rat tissues after oral administration of the acid.