[Features of tissue differentiation of the thyroid gland in residents of Magadan].

The histological structure and morphometric parameters of the thyroid gland were examined in fetuses, newborns and infants during the early postnatal period to assess the peculiarities of thyroid differentiation in Magadan goiter endemic region. It was demonstrated that fetal thyroid gland remained immature. Functional strain of thyroid structures was shown in neonatal period that is considered to be the manifestation of the adaptive responses of the newborn. In infants aged 2-3 months thyroid gland attained definitive morphometric parameters that indicated its functional maturity. Low rate of tissue differentiation in the thyroid gland during prenatal period may result from iodine deficiency in both mother and fetus, which is aggravated by the unfavorable natural climatic factors of the North.