C cells in the thyroid of pinealectomized rats

purpose: to study quantitatively c cells in the thyroids of non-isogenic rats to determine the possible effects of pinealectomy on the number of these cells, and consequently on the synthesis and secretion of calcitonin. methods: twenty male rats of an outbred strain (200-300 g) were used in the present study. one group of 10 animals was pinealectomized 50 days prior to sacrifice. thyroid tissue was stained for calcitonin (dako corporation) at a 1:1500 dilution. the number of c cells observed was expressed as number of cells/cm2. data were analyzed statistically by mann-whitney test. results: the number of c cells in pinealectomized and normal animals ranged from 489 to 2084 per cm2 and 227 to 1584 per cm2, respectively, a difference that was statistically significant (p <0.05). conclusions: these results showed consistent differences in the number of c cells after pinealectomy when compared to controls. we believe that pinealectomy increases the number of c cells in the rat thyroid.