In the monograph the structural organization of epithelial and stromal tissues in norm and pathology, mechanisms of regulation of cell proliferation and differentiation, the problem of age involution are considered. There are own data which reveal the peculiarities of structurization of epithelium and stroma, tumor tissue. The concept of morphofunctional zones and functioning of cambial cells in them are developed. The most characteristic fundamental features of cambial cells and the key mechanisms leading to development of malignant tumors are revealed. The concept of morphofunctional zones developed by authors allowed to reveal the important factors leading to aging and death of the organism. The complex analysis of own experimental results and literature data allowed to define the key proteins which participate in these processes. The monograph is addressed to biologists, oncologists, pathologists.