Seasonal changes in intra‐ and interorgan occurrence of rodlet cells in freshwater bream

Abstract

Significant seasonal differences in intra‐ and interorgan prevalence, abundance and distribution of rodlet cells (RC) were observed in freshwater bream caught in May and August 1997 from a PCB‐polluted lake, Lake Kernaala, Finland. In May, the majority of RCs in liver were seen in blood vessel endothelium, while in August most cells were located in the epithelium of the intrahepatic biliary ducts. In kidney, a significant increase in RCs in the columnar epithelium of the collecting ducts was observed from May to August. RCs in spleen were extremely rare in May, but were seen frequently in the endothelium of the splenic blood vessels in August. In gill and intestine, RCs were found in every tissue sample studied, with no statistical differences in their abundance or distribution between seasons. No RCs were seen in gonads. Total numbers of RCs increased dramatically from May to August in kidney and in spleen. The frequency of RCs corresponded strongly with the current phase of parasitic infections in liver, kidney, and spleen. It is concluded that RCs play a role in host defence mechanisms in fish, displaying induced expression at the times of peak parasitic prevalences.

A quantitative study of the hepatic eosinophilic granule cells and rodlet cells during the breeding cycle of Ohrid trout, Salmo letnica Kar. (Teloestei, Salmonidae)

“…Fewer RCs in May and June as compared to August and September were also reported for some non-salmonid species [16]. Also in the freshwater bream, Abramis brama L., differences in RC prevalence, abundance and distribution were found between specimens in pre spawning, and in spawning or just after spawning [18]. In addition to seasonal and/or gonadal related influences, RCs can proliferate in response to parasitic infections, to xenobiotics action [2,7e9,29], and even to crowding stress [16,30].…”

“…RCs have been identified in the liver of brown trout, Salmo trutta L. [17], and of some non-salmonid species [8,11,18]. Considering the EGCs, to our best knowledge their presence in the liver has only been reported in a few non-salmonid species [8,19].…”

Inflammatory cells of teleostean fish: A review focusing on mast cells/eosinophilic granule cells and rodlet cells

“…A study on myxosporean infections in the gilthead sea bream, showing appearance of rodlet cells in infected tissues [96], and another by Koponen and Myers [97], recording seasonal changes in rodlet cell number in the freshwater bream, also support the suggestion that rodlet cells play a role in host defence.…”

The rodlet cells of teleostean fish: their potential role in host defence in relation to the role of mast cells/eosinophilic granule cells

“…Also in these species I found an association between the occurrence of trematodes or cestodes in the intestine and the presence of rodlet cells in the intestinal epithelium, and encysted larval specimens of trematodes, cestodes or nematodes in the intestine or adjacent tissues seemed to induce recruitment of rodlet cells to the mesothelium of the viscera and secretion of their products onto the mesothelial surface [23]. Subsequent observations by Dezfuli et al [24,25] in the trematode-infected eel and the nematode-infected minnow, respectively, by Palenzuela et al [26], studying myxosporean infections in the gilthead sea bream, and by Koponen and Myers [27], recording seasonal changes in the occurrence of rodlet cells in freshwater bream, also support the suggestion that rodlet cells play a role in host defence mechanisms in fish.…”