Distribution of silver in the eyes and plasma proteins of the albino rat.

Albino rats were given a 0.25% solution of silver nitrate to drink for 10 weeks, then were divided into two groups. One group continued to drink the solution for an additional 6 months, while the other group was given water to drink for an additional 12 months. The ingestion of silver nitrate retarded the growth of the rats and eventually caused their death. The rats regained weight and appeared to grow normally when the silver nitrate regimen was withdrawn. Radioactive silver in the plasma was found to be almost exclusively in a single electrophoretic protein band. Examination of the rats' eyes by electron microscopy showed deposits of silver particles in Bruch's membrane, the basement membranes of the choriocapillaris and the ciliary processes, and the stroma of the choroid and ciliary processes. The number and size of the particles increased with continued ingestion of silver but decreased if the silver regimen was withdrawn after the initial 10 weeks of ingestion. Fine particles of silver were still present 12 months after the end of the ingestion of silver nitrate. At no time were silver particles seen in the basement membranes or endothelial cells of the retinal capillaries or within the cytoplasm of the pigment epithelium or the epithelial cells of eh ciliary processes.