A critical re-evaluation of the anisotropic index used in polarization microscopy: a study on epiphyseal cartilage.

Topo-optical reactions specific for collagen and glycosaminoglycans were performed on epiphyseal cartilage plates which differed in age, in chemical composition, and in structure. Retardation values were measured with the polarization microscope and anisotropic index values were calculated after each reaction. It was found that the anisotropic index proposed earlier for quantitative evaluation of topo-optical reactions did not refer either to the submicroscopic orientation pattern or to the quantity of cartilage matrix components. It is suggested that retardation values of induced birefringence may be only used to characterize the spatial orientation of these components in the cartilage matrix.