[Cellular renewal in the parenchyma and stroma of the parathyroid glands]

By means of autoradiographic, morphometric and cytophotometric methods main parameters, characterizing processes of cellular renewal have been studied in the parathyroid glands of 66 mature white male rats with body mass of 160-230 g. The time of renewal of the parathyrocyte population is 80-100 days, the average daily mitotic index--0.88 +/- 0.09% 0, the average duration of mitosis--1.61 h, the average daily index of dying cells--0.24 +/- 0.03% 0. The greatest mitotic activity of parathyrocytes is revealed in the evening and early in the morning. At night together with decreasing amount of dividing cells, content of dying parathrocytes increases. The glandular cell population is mainly diploid, polyploid cells make no more than 0.1%. The time of renewal of stromal cells makes 82 +/- 9 days. The results obtained demonstrate that the parathyroid cells should be considered as a slowly renewal population.