[Age and changes in the thyroid gland of A/He mice (morphometric and histochemical studies)].

Changes in the thyroid gland of mice A/He in postnatal ontogenesis were studied at the age of from 1 to 547 days by methods of morphometry and quantitative histochemistry. During the first days of life an active growth of the organ, accumulation of colloid, increase of the relative volume of the follicular epithelium in which the intensity of the histoenzymological reactions increased were observed. In the period of sex maturation the excretion of colloid was noticed as well as an increase of the height of follicular cells with activation of some of their enzymatic systems. Later on, while aging, the follicular cells gradually become flatter, the level of some enzymatic reactions of thyrocytes drops, the relative volume of colloid increases and its histochemical properties change. In the gland of animals older than 6-7 months well pronounced cystic changes were found.