Thyrotropin stimulated colloid droplet formation in the thyroid of hypophysectomised mice after calcitonin...

The influence of calcitonin on colloid droplet formation in the thyroid gland of hypophysectomised mice after thyrotropin (TSH) stimulation was investigated. Calcitonin was injected 30 min before TSH administration. 30 min after TSH the colloid droplet index in the thyroid cells was twice as low in the calcitonin group in comparison with the control one (0.111 +/- 0.020, 0.228 +/- 0.025 respectively). 60 min after thyrotropin treatment the number of colloid droplets was higher in the animals treated with calcitonin (0.135 +/- 0.093) in comparison with the control group (0.083 +/- 0.025). The possible mechanism of calcitonin action on colloid droplet formation is discussed.