Histopathology of Hematodinium sp. infection in Crangon crangon . (A) Low power image showing distension of hepatopancreatic haemal sinuses with masses of Hematodinium sp. parasites (asterisk). Hepatopancreatic tubules are shrunken and are depleted of lipid inclusions (arrows). Scale 200 μm. (B). Single hepatopancreatic tubule (arrow) surrounded by masses of Hematodinium sp. parasitic life stages (asterisk) within the distended haemal sinuses. Scale 100 μm. (C) Hepatopancreatic tubule co-infected with Crangon crangon bacilliform virus (CcBV) (arrow) (Stentiford et al. 2004). Hematodinium sp. parasite life stages are seen within the haemal sinuses (asterisk) Scale 50 μm (D). Ovary, apparently arrested in pre-vitellogenic status. Oocytes do not contain vitellogenesis and oogonia are often apoptotic (arrow). Parasite life stages are in direct contact with oocytes (asterisk). Scale 100 μm. (E). Skeletal musculature within a walking appendage. Atrophy of muscle fibres is accompanied by colonisation of haemal spaces with masses of parasite cells. Scale 200 μm. (F). Attachment of filamentous trophonts to remnant basement membranes (arrow) within the atrophied skeletal musculature. Scale 25 μm. All images H&E histology.