Developmental change in calcitonin secretory capacity of fetal rat thyroid C-cells

Developmental changes in calcitonin (CT) secretory capacity of C-cells were studied by using primary cultures prepared from the thyroid glands of rat fetuses at 16th, 18th and 20th day of gestation and the thyroid glands of 28-day-old rats. Both CT content of C-cells and high Ca2(+)-stimulated CT secretion increased with the age of the rats. The ratio of secreted CT to the CT content of C-cells also increased according to the age. These results demonstrated the functional development of C-cells during the fetal period.