Presence of rodlet cells and other inflammatory cells in Sparidae infected by Mixosporidia.

Histopathological survey was carried out in myxosporeans infected sparids cultured in different systems in Italy. Two hundred-forty sea bream (Sparus aurata) and 28 sharpsnout sea bream (Diplodus puntazzo) were examined. Myxidium leei were detected in 8 sea bream (Sparus aurata) and 21 sharpsnout sea bream (Diplodus puntazzo); Polysporoplasma spans in 2 sea bream; Henneguya sp. in 4 sea bream; Polysporoplasma spans associated with Henneguya sp. in 1 sharpsnout sea bream. Histological sections: were prepared from gill, lever, gall bladder, gut, pancreas, kidney, spleen, heart and brain and stained with Haematoxylin and Eosin (H&E), Giemsa, Periodic Acid-Schiff (PAS), Mallory's Trichrome and Ziehl Neelsen Methods. Histopathological lesions observed in the gut infected by Myxidium leei were: severe enteritis, detachment of epithelium, haemorrhages and inflammation of the subepithelial connective tissue with massive presence of eosinophilic granule cells (EGGs), particularly in sharpsnout sea bream. Polysporoplasma spans was found in the trunk kidney determining serious damages only in sharpsnout sea bream. Glomerular capillaries were invaded by the parasite. Spores were also detected in the lumen of renal tubuli, in the interstitial tissue and in cysts replete with cellular debris. Inflammatory responses consisted mainly of melanomacrophages near spores degenerated and EGCs. The presence of rodlet cells inside the cysts and in the nephric tubules were distinct after staining with Mallory's Trichrome. Henneguya spores discovered in sharpsnout sea bream were evident free in the kidney interstitial tissue and damaged in melanomacrophages centres. Henneguya sp. was found in cysts on the bulbus arteriosus of sea bream. Foci of infection were observed throughout the musculature and elastic fibres of the bulbus. EGGs and rodlet cells were abundant in the wall.