[Proliferative activity of typical thyrocytes and C cells in normal and regenerating thyroids]

By means of quantitative methods (autoradiography, estimation of the mitotic index of cells, morphometry) proliferative activity of typical (follicular) thyrocytes and C cells (calcitonicytes) has been studied in 40 rats both in control and in 1-30 days after hemithyroidectomy. For revealing C cells silver nitrate impregnation after Sevier-Munger and metachromatic reaction with toluidine blue in Sawicki's modification have been used. At repeated injections of 3H-thymidine (12 injections of 0.8 mcCi/g with the interval of 8 h) in the intact rat thyroid glands and equal amount (2-3%) of endocrine cells of the both types are labelled, in 2.5-6 days after a partial resection, amount of the labelled follicular cells increases by 10 times, while that of calcitonicyte--only by 2 times. The differences revealed can be connected with more pronounced histogenic potencies of the typical thyrocytes, realized most fully under conditions of their specific hormonal stimulation in the course of the gland restoration.