A New Vaginal Smear Assay for Vitamin A in Rats

A method is described for measuring the relative activities of vitamin A active substances based on their direct effect on the cornified vaginal epithelium of vitamin A-deficient rats. The results obtained agree well with those found in the tracheal organ culture assay. The relative activities found for several test compounds were: all-trans-retinoyl-β-glucuronide >all-trans-retinoic acid >all-trans retinol >all-trans-5,6-epoxyretinoic acid. The assay is simple and inexpensive to perform, and should find use in laboratories where the equipment and personnel required for the tracheal organ culture assay are not available. retinoic acid retinol 5,6-epoxyretinoic acid retinoyl-β-D-glucuronide ovariectomy vaginal cornification rat