Histological variations of hepato-splenic organs from the North Sea dab, Limanda limanda (L.)

Abstract. This study showed variations in the histological appearance of livers and spleens from the North Sea dab, Limanda limanda (L.), sampled during two cruises of the FFS Anton Dohrn (5–15 January 1981 and 12–23 October 1981). Samples were taken from the German Bight, Dogger Bank and Humber/Thames areas of the North Sea. The majority of livers and spleens were assumed to be normal; however, certain histopathological changes were noted which included the abundance and size of melanin–macrophage centres where Fe⁺⁺⁺ was demonstrated, sites of focal necrosis, the presence of hepatic nodules, the occurrence of granulomas and hepatic hyperaemia. The areas containing Fe⁺⁺⁺ in spleens were quantitatively assessed and found to be increased in size and frequency in dabs sampled from the Dogger Bank. It was also noted that the prevalence of hepatic nodules was higher in dabs from that same area. Although this study does not reveal reasons for the variations in prevalences of anomalies, the pathologies are discussed in relation to habitat and environmental conditions.