Ultrastructural localization of exogenous silver in the anterior pituitary gland of the rat.

Silver accumulations in the anterior pituitary of argyric rats were demonstrated using a histochemical method that visualizes minute traces of the metal. Silver was localized intra- and extracellularly throughout the anterior pituitary. Intracellular deposits were found within the lysosomes of somatotrophs and gonadotrophs. Extracellularly, the grains were located in basal laminae of portal veins and sinusoidal capillaries and in the membrane separating the anterior pituitary and part intermedia. The amount of deposited silver was dependent upon the dose of silver administered. Increasing the dose of silver lactate from 10 to 30 mg resulted in increased deposition, whereas a further increase to 60 mg did not alter the amount of silver deposited.