Figure 2.

Histopathology of select MS222 target-organs from zebrafish. Hematoxylin and eosin, scale bar = 20 µm. Gills (A through C), kidneys (D through F), liver (G through I), and ventral coelomic skin (J through L) of naïve zebrafish (A, D, G, J) were histologically indistinguishable from zebrafish exposed to fresh MS222 (B, E, H, K) and MS222 stored at -20 °C for 6 mo (C, F, I, L). Hepatic megalocytosis (arrows) was seen across all treatment groups and did not follow a treatment-related trend.