Microscopic distribution of Americium-241 in the beagle thyroid gland.

Abstract 241Am deposition in the beagle thyroid gland occurred principally in the interfollicular areas. Lesser amounts were also retained in the tunica media and/or intima of some of the arterioles. Retention in the follicular epithelium, the colloid, and the collagenous structures, such as the capsule and interlobular septa, was low. There was no significant change in this general distribution pattern over a period of 448 days.