NADPH-d activity in rat thymus after the application of retinoid acid

The aim of this work was to determine the localization of nicotinamide-adenine dinu-cleotide phosphate-diaphorase (NADPH-d) activity as the marker for synthesis of nitric oxide synthase (NOS) in the rat thymus after the application of retinoid acid (RA) on 1st, 7th, 14th and 21st days of gestation. The given results can build the basis for understanding of the role of NOS in rat thymus. NADPH-d posi-tive cells were represented with dark-blue color and were localized on corticomedullar junction of the thymus. These cells were of dif-ferent intensity of coloring and were shaped in oval, circle or irregular forms. NADPH-d posi-tive nerve fibers were observed in perivascular topography. They were marked more strongly in the case of control group. The result of appli-cation of RA to gravid rats was that the birth weights of newborn rats and their thymuses were smaller, but without statistically signifi-cance