Glycogen vacuolation is reduced in the livers of DDVP–exposed fish. a The liver of exposed fish shows decreased hepatocellular vacuolation compared with control animals (yellow arrows). Representative images of transversely sectioned hematoxylin and eosin stained livers from a control and a unexposed fish (high concentration) are shown. Bars are 25 μm. b Periodic Acid-Schiff (PAS) staining reveals reduced levels of glycogen in the livers of exposed fish. Liver sections from controls and fish exposed to high and low concentrations of DDVP were semi-quantitatively scored for PAS-positive glycogen staining (0-4+, low to high staining intensity). All unexposed fish were scored “3 + .” Scores for the low concentration-exposed fish ranged from 2 + −4+ (mean = 3+), and all the fish exposed to the high concentration were scored “0–1+”. Exposed fish differed from control at p ≤ 0.05 level using the Kruskal-Wallis test. The high concentration exposure was significantly different from control in post hoc testing with the Wilcoxon ranks test (p ≤ 0.05)

Effects of DDVP exposure on non-neural tissues. Representative images of hematoxylin and eosin stained transverse tissue sections are shown. Bars are 25 µm except for kidney which are 50 µm. Skeletal muscle: Separation between myofibers is a processing artifact. Treated fish show myodegeneration, with sarcoplasmic vacuolation in myofibers (arrows) and no obvious repair or inflammatory response. Testis: The germinal epithelium is thin in contols and the seminiferous tubules contain abundant spermatozoa while testes from treated fish show degeneration with germ cell syncytia (thin blue arrow) and clusters of apoptotic germ cells having pyknotic nuclei and hypereosinophilic cytoplasm (yellow arrow). The germinal epithelium is thicker in treated fish than in controls with a higher proportion of spermatogonia and smaller lumina with fewer spermatozoa. Pancreas: Acinar cells from controls contain fine red intracytoplasmic zymogen granules (arrow), but those from exposed fish are small due to granule depletion. Caudal kidney: Sinusoidal capillaries are congested and distended with erythrocytes (yellow arrows) in treated fish.