Transfer of fluorescent microspheres from the integumental tissues to the kidney and spleen in rainbow trout [Oncorhynchus mykiss]

In a previous study, we immersed rainbow trout Oncorynchus mykiss in a suspension of 1 mu m diameter fluorescent microspheres and found that microspheres adhered to the injured epidermis of the integument. Some of those microspheres were endocytosed by the migrating epithelial cells which covered the injury surface during healing process, and later also by macrophages. The present study aimed to confirm morphologically whether suspended fluorescent microspheres which had been internalized in the integumental tissues could be found in the kidney and spleen. Microspheres were found in the kidny and spleen 8 and 20 days after the immersion. They were fround in the melanin-laden macrophages of the integment and concurrently in the melano-macrophages centers of both the kidny and spleen.