[en] I¹³¹ injected to rabbits immunized with homologous thyroid gland on the 19th - 20th day of pregnancy led to congenital disturbances of the thyroid gland in the experimental litters in the first and second generations. The functional activity and the activity of proteolytic enzymes of the thyroid gland descreased by the 30th day of the postnatal development. A distinct correlation was revealed between the contents in the thyroid gland of the experimental litters of DIT+MIT and of organic forms -T₃+T₄. During the first days after birth the DIT+MIT content showed a sharp fall and increased by the 30th day; on the contrary, iodine binding into organic forms decreased with the age. Histological examination of the thyroid glands in the experimental litters demonstrated lymphoid-plasmocytic infiltration, along with connective tissue proliferation, which led to a marked sclerosis and fibrosis of tissues, hypofunction. Beginning with the age of one month there was observed an extensive nodular proliferation, which possibly served as the beginning of the parenchymatous goiter formation. The appearance of lymphoid-plasmocytic infiltration in the thyroid gland of the second generation could be considered as the result of a congenital predisposition to the autoimmune thyroiditis inlaid in the memory cells and intensified during birth