Fig. 7.

Tetracapsuloides bryosalmonae infecting Oncorhynchus mykiss. Stages in kidney, spleen, and liver tissues of infected rainbow trout. (A) Numerous interstitial pre-sporogonic stages of the parasite (arrows); proliferation of the interstitial tissue can be seen in the kidney. (B) Interstitial stages in the kidney (arrows) and interepithelial stages of the parasite in kidney tubules (arrowhead). (C) Pre-sporogonic parasite stages in the spleen (arrows). (D) Parasite stages in the liver (arrows). All sections were stained using immunohistochemistry and a hematoxylin counter-stain