Lesions caused by Monogenean parasites on gill tissue and chloride cells of Caspian Sea white fish

Monogeniasis is one of the most common diseases that happen by a species of Monogenean parasite in the gills and skins of many farmed and wild fish and it is seen in all age of them. In this research that it was done on December 2012, caught 33 white fish (Rutilus frisii kutum) weight 190- 1200 g and length 20-40.5 cm from the southern coast of the Caspian Sea in province of Mazandaran (Sari) were examined. Gill arch in 10% fixed formalin and by using standard histological methods, 5 µ tissue sections of samples were taken and by hematoxylin - eosin method they were staining. After studying tissue losses which were caused by parasites, chloride cells number and their size were couned and measured through optical microscope. Monogenea were identified from Dactylogyridae and Diplozoidae families. Mean infection intensity and frequency to parasites of Dactylogyridae and Diplozoidae families were respectively (118 , 100%) (4.53 , 78.78%). The observed loss included: filaments demolition and adhesion of gill lamellae, epithelial cells hypertrophy and hyperplasia of gill blades, separating the epithelium from the basement membrane of blades, the incidence of aneurysm and clubbing mode.The results showed that total chloride cells number in the presence of parasites decreased but there weren,t any changes in their size. There was a strong and significant inverse correlation relationship between parasites density and total number of these cells.