Fig. 4From: Comparative toxicity and biodistribution assessments in rats following subchronic oral exposure to copper nanoparticles and microparticlesHistopathological changes in spleen and thymus of rats treated with copper nanoparticles (Cu NPs) and copper microparticles (Cu MPs) following 4Â weeks-repeated oral dose. The rats treated with Cu NPs at 400Â mg/kg/day showed moderate to severe degree of atrophic white pulp, decreased number of follicles and cellularity, and yellow pigmentation in spleen, disrupted demarcation of medulla/cortex, decreased cellularity of medulla/cortex, and cytoplasmic vacuolation in thymus. There were no changes in spleen and thymus from rats treated with Cu MPs. Hematoxylin and eosin stainBack to article page