The problem of colloid pressure of influence on the thyroid gland folliculogenesis is not clear enough in the scientific literature. The purpose of this study was to investigate the mechanism of folliculogenesis in the thyroid gland under the influence of salts of heavy metals combinations on the organism. The research was conducted on 24 white adult rats. To study the dynamics of morphological changes animals were removed from experiments on 30 and 60 days. Based on the theory of thin shells and the results of morphometric study of both groups of adult rats, which were influenced by a combination of heavy metal salts, the mathematical model to determine the level of tension in the wall of follicles was deduced. As a result of the influence of combinations of heavy metal salts on the follicular apparatus thyroid hypoactivity developed, which manifested in accumulating colloid and changing its tinctorial, physical and chemical properties, reducing the height of follicular epithelium, follicles increase in diameter, which also reflected the increasing tension in the wall of the follicle. Thus, the results allow to conclude that there is a significant role of intrafollicular colloidal pressure on the process of folliculogenesis. It is determined that in the wall of the elliptic form follicle higher tension arises in longitudinal section of the ellipse, and in cross-section the tension decreases. Analyzing the research results, we can assume that the difference between peripheral and central folliculogenesis occurs because of different amounts of intrafollicular pressure, which again are derived from different functional activity of the follicular epithelium.