[Changes in the ultrastructure of the anterior lobe of the pituitary after subjecting animals to cooling].

Stress reactions caused by extreme factors have a common nonspecific main component-a release of ACTH into the blood stream and increased functional activity of corticotropic cells of the anterior lobe of the hypophysis. Qualitative properties of the acting agents depending on their nature determine other adaptive changes of hormonal and metabolic processes in the organism after the interference. The study of the dynamics of the ultrastructure of glandular cells of the rat's hypophysis anterior lobe after a single severe cooling has revealed a sharply pronounced early mobilization of thyreotrops. The increased thyreotropic activity is an additional specific component of stressor reaction which is caused by cooling. The electron microscopic study of the structure and topography of glandular elements has revealed a cycle of functional-morphological changes completed within a day after the exposure.