[The reaction of the thyroid neural structures in guinea pigs to ionizing radiation exposure].

State and structural organization of the guinea pig thyroid gland were studied histochemically in distanced terms (6 months) after the single external x-ray radiation 12.9 C/kg in doze. with the following intraperitoneal introduction of 131 6.5 C/kg in doze. Atrophically changed zones of parenchyma were observed along with regions of extra- and intrafollicular hyperplasia with compensatory-adaptive manifestations aimed at hormonopoiesis increase. Growth of sympathetic innervation of the vessel walls and around the follicles were found in areas of high functional activity. Direct contact between adrenergic axons and thyrocytes was demonstrated by means of electron microscopy. In parenchyma areas with signs of atrophia, adrenergic nerve fibers and terminals are located only in vessels. Thus, connection between the state of the thyroid gland sympathetic innervation and structural organization of its parenchyma in distanced terms of radiational effects was followed up.