[Thyroid regeneration in various localizations of resected fragments of the organ]

Structure and function of the regenerating thyroid fragment were studied in 18 adult white rats 30 days after partial resection of centromedial or peripheral fragments of the lobes similar in size using quantitative methods (organometry, histometry, measurements of blood serum hormones). The volume of glandular tissue removed in two series of experiments was 40 and 75% of the total thyroid mass of experimental animals. Centromedial portions of the thyroid of intact rats were characterized by greater follicular epithelium volume (by 10%) and C-cell content per section area (six-fold), as well as by a lesser mean diameter of the follicles (by 26%) and colloid volumic fraction (by 40%) in comparison with the peripheral segments. No reliable differences in the quantitative structural parameters (mass, tissue component volumic fractions, mean follicular diameter and follicular epithelium height) and hormonal activity of the regenerated tissue in the two variants of surgery were observed. The results indicate that thyroid parenchyma of various portions of the organs is similarly capable of full-value regeneration.