The effects of adrenalectomy and hydrocortisone replacement on the thyriod of the adult male rat I. Morphometrical data and histochemistry of some oxidative enzymes.

Morphometrical and histochemical studies were performed to determine the effects of adrenalectomy and hydrocortisone replacement on the rat thyroid. It follows from the performed studies that morphometrical and histochemical changes in the rat thyroid induced by adrenalectomy or hydrocortisone replacement depend upon the duration of the experiment. From the 4th day of the experiment adrenalectomy results in an increase in the volume fraction of the epithelium of the thyroid vesicles with a concomitant decrease of the colloid fraction. As compared to sham operated animals on the 10th day of the experiment the increase in the height of the epithelial cells was seen. Hydrocortisone replacement partially prevents the thyroid changes induced by adrenalectomy, however, this hormone markedly increases the volume fraction of the thyroid stroma and the height of the epithelial cells. On the other hand, histochemical reactions for various oxido-reductases do not provide helpful information for evaluation of the secretory activity of the rat thyroid. It follows from our results that adrenalectomy enhances thyroid stimulation by TSH and enhances the secretory activity of this gland, effects partially prevented by hydrocortisone replacement.