Liver histopathology of Baltic grey seals (Halichoerus grypus) over three decades

• The liver plays an important role in the metabolism and elimination of endogenic and exogenic lipid-solublecompounds. Multiple studies have shown that polychlorinated biphenyls (PCB) and dichlorodiphenyl trichloroethane(DDT) lead to morphological changes in liver cells. The aim of the present study was therefore toanalyse liver changes over time in Baltic grey seals (Halichoerus grypus) and to correlate these with historical PCBand DDT contaminations. A total of 191 liver samples were collected between 1981 and 2015 in the Gulf ofBothnia and northern Baltic Proper. Six histological features were evaluated, including portal mononuclear cellinfiltration, random mononuclear cell infiltration, lipid granulomas, hepatocellular fat vacuoles, hepatic stellatecells and mild multifocal bile duct hyperplasia accompanied by portal fibrosis. Three of the six lesions showed asignificant correlation with age. Furthermore, a positive correlation between portal mononuclear cell infiltrationand mild multifocal bile duct hyperplasia was found. Additionally, lipid granulomas were significantly correlatedwith hepatic stellate cells. More importantly, hepatic stellate cells and mild multifocal bile duct hyperplasia werecorrelated with adipose tissue (blubber) concentrations of ƩPCB, measured in a subsample (n = 34) of all individuals.No correlation with lesions and ƩDDT concentrations were found. These results show that age is animportant factor for the development of these liver lesions, but PCBs burden may be an influencing factor. This isin agreement with previous studies of marine mammals in the Baltic Sea as well as in the Arctic. We thereforeconclude that not only age of the animals, but also exposure to PCBs should be taken into account when understandingand evaluating the current health status of Baltic grey seals.

Ämnesord

LANTBRUKSVETENSKAPER  -- Veterinärmedicin -- Patobiologi (hsv//swe)

AGRICULTURAL SCIENCES  -- Veterinary Science -- Pathobiology (hsv//eng)

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Nyckelord

Man and the environment

Naturmiljö och människan

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