Cellular alterations in different organs of European sea bass Dicentrarchus labrax (L.) exposed to cadmium L. Giari a , M. Manera b , E. Simoni a , B.S. Dezfuli a, * a Department of Biology, University of Ferrara, Via Borsari, 46, 44100 Ferrara, Italy b Department of Food Science, University of Teramo, I-64100 Teramo, Italy Received 4 July 2006; received in revised form 29 September 2006; accepted 25 October 2006 Available online 22 December 2006 Abstract Specimens of farmed European sea bass (Dicentrarchus labrax L., 1758) were exposed to different cadmium (Cd) concentrations (4.47, 5.63, 7.08 and 8.91 mg l À1 ) for 24 and 48 h. The effects of Cd on numbers of some cell types and structures (i.e., chloride cells, CCs; macrophage aggregates, MAs; rodlet cells, RCs) and on structure and ultrastructure of the main organs (gill, liver, intestine, kidney) were studied with routine process for light and transmission electron microscopy. Following cadmium exposure, the numbers of branchial CCs as well as intestinal and renal RCs increased significantly within 24 h. Increase in metal concentration did not affect the magnitude of the numerical increment of the aforementioned cells. Moreover, in treated fish (24 and 48 h) the numbers of MAs in both head kidney and spleen were significantly higher than in control conspecifics, whilst the global area of MAs was less influenced by the acute treatment. In exposed sea bass, all the examined organs exhibited cellular modifications which appeared time- and dose-dependent. The gills showed telangectasia, lamellar fusion, oedema, epithelial lifting and leukocyte infiltration. In the liver, kidney and intestine acute cell swelling and vacuolization were common. Ultrastructurally the alterations observed frequently in hepatocytes, tubular epithelial cells and enterocytes included presence of numerous myelinoid bodies, damaged mitochondria, dilatation of endoplasmic reticulum, high number of lysosomes and autophagolysosomes. In intestinal and kidney tubular epithelia of treated fish, rodlet cells displayed some anomalies like dilatation of nuclear envelope, cytoplasmic vacuolization, presence of myelinoid bodies, rodlets degeneration and exten- sive discharge activity. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Cadmium; Dicentrarchus labrax; Rodlet cells; Histopathology; Ultrastructure; Biomarkers 1. Introduction The exposure of fish to chemical contaminants induces a number of modifications in different organs, particularly gills, kidney and liver, which histological examination represent a useful tool to assess the effects of xenobiotics (Bernet et al., 1999; Dezfuli et al., 2006). A wide range of histo-cytological alterations in fish have been developed and recommended as biomarkers for monitoring the pollu- tion (Stentiford et al., 2003; Au, 2004). Biomarkers are defined by Peakall (1994) as sub-lethal biological measures of response to and effects of pollutants in living organisms. The modifications at histological and cellular levels are relatively easy to determine, occur before the growth and reproductive changes, and can be better related to health and fitness of individuals than a single biomolecular/ biochemical parameter (Teh et al., 1997; Au, 2004). Cadmium is a common aquatic toxic metal pollutant of important ecological and human health concern and it is detectable in critical amounts in many parts of the world (Schultz et al., 1996; Iliopoulou-Georgudaki and Kotsanis, 0045-6535/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2006.10.061 * Corresponding author. Tel.: +39 0532 291701; fax: +39 0532 291715. E-mail address: dzb@unife.it (B.S. Dezfuli). www.elsevier.com/locate/chemosphere Chemosphere 67 (2007) 1171–1181