Morphophysiological characteristics and peculiarities of adrenal gland of bank vole (Clethrionomys glareolus) were studied in the area of natural biogeochemical province with abnormally high content of nickel, cobalt and chromium. The control population inhabited area with usual content of these elements. We used 4-factor analysis of variance to estimate the influence of geochemical conditions, phase of population cycle, sex and reproductive state on the morphophysiological characteristics of animals and functional activity of adrenal gland. Animals from area with high concentration of Ni, Co and Cr show an increase in relative mass of adrenal glands, fascicular zone of adrenal cortex, size of cells and their nuclei. All these changes can be considered as an evidence of increased secretion of glucocorticoids. It is shown that phase of population cycle influences fatness of animals, size of nuclei, cells and adrenal cortex. Females in comparison with males are characterized with higher indexes of liver and adrenal gland, as well as morphometric indexes of adrenal cortex. The maturation of animals is accompanied with increase in body mass, fatness and relative mass of adrenal glands, the size of cortex zone, nuclei and cells themselves. It is supposed that the effect of "geochemical factor" results in intensification of glucocorticoid secretion of adrenal costex, thus increasing non-specific resistance of animals inhabiting area with high concentration of heavy metals. Such factors as "phase of population cycle", "sex" and "reproductive state", influence mineralocorticoid activity, glucocorticoid and androgenic functions of adrenal cortex. Some factors show synergetic effect.
