This is the second communication of a series of publications on Russian studies in the field of optical coherent tomography (OCT), the newest noninvasive highly resolving technology of visualization of the structure of biological tissues. By using the investing tissues as an example, this paper demonstrates the universal types of changes in their optical properties. Optimal images permit differentiate benign and malignant processes with a high degree of diagnostic accuracy. Diverse benign processes occurring in the epithelium are detected on the OCT images as changes in its height, the scattering properties and stroke of a basilar membrane. The absence of any structure on the image is the main OCT criterion for malignancy. The diagnostic efficiency of OCT is high in recognizing neoplasia of various mucous membranes: the sensitivity of the technique is 77-98%; its specificity and diagnostic accuracy are 71-96 and 81-87%, respectively.