In experiments on 40 white sexually mature nonlinear male rats, applying a correlation-optical investigation the author has revealed the presence of heterogeneity of an optically active crystalline substance under conditions of the development of tubulo-interstitial syndrome which is indicated by its characteristics: intensity, ellipticity, the index of double refringence. More sensitive criteria for early diagnosis of tubulo-interstitial syndrome based on the degree of an increasing content of the crystalline substance as a collagen marker, are asymmetry and excess rather than the average value and dispersion.
