Faculty of Veterinary Medicine University of Zagreb
Abstract
Sub-lethal toxicity of zinc chloride (11.5 ppm) on the respiratory organs of the Channa striata has been analysed. The mucous cells show periodic fluctuations in their number, size and staining properties elaborating larger quantities of sulphated mucopolysaccharides. The respiratory epithelium (RE) of the respiratory (secondary) lamellae (SL) of the gills shows periodic lifting with deformity of the lamellar elements, haemorrhages due to necrosis and sloughing off of the RE, followed by hyperplasia and fusion of neighbouring SL. Other prominent alterations include increased thickness of the RE and subsequent dismantling of the vascular elements. Fusion of SL reduces the surface area for gaseous exchange, causing impaired branchial respiration. The alterations in the suprabranchial chamber include protrusion of RBC-engorged minute vascular papillae on the floor of its lumen. This brings the blood nearer to the air in the lumen. Congestion of the sub-epithelial blood vessels of the respiratory organs, especially the suprabranchial chamber, takes place following exposure.Analizirana je subletalna toksičnost cinkova klorida (11,5 ppm) na dišne organe riba Channa striata. Sluznične stanice pokazivale su povremene promjene u broju, veličini i osobitostima bojanja s izraženom većom količinom sulfatnih mukopolisaharida. Epitel dišnih (sekundarnih) nabora škrga povremeno se otkidao što je dovelo do njihova oštećenja te krvarenja zbog nekroze i ljuštenja dišnog epitela s posljedičnom hiperplazijom i spajanjem susjednih dišnih listića. Druge promjene očitovale su se u vidu zadebljanja dišnog epitela i oštećenja krvožilja. Spajanje dišnih listića smanjilo je površinu za izmjenu plinova dovodeći do oslabljenog branhijalnog disanja. Promjene na suprabranhijalnoj komori dovele su do zadebljanja sićušnih papila na bazi lumena žila. Time se krv našla bliže zraku u lumenu. Nakon izloženosti došlo je do zadebljanja subepitelnih krvnih žila dišnih organa posebice suprabranhijalne komore
