European Journal of Biomedical and Pharmaceutical Sciences

A RESPONSE STUDY ON DENDRITIC ORGANS OF A BOTTOM DWELLING FRESHWATER EDIBLE CATFISH CLARIAS BATRACHUS (LINN.) FOLLOWING LONG – TERM EXPOSURE AND WITHDRAWAL OF SODIUM ARSENATE HEPTAHYDRATE (NA2HASO4.7H2O) STRESS

Ajai Kumar Singh*

ABSTRACT

The dendritic organs of Clarias batrachus (Linn.), a nutritionally important bottom dwelling freshwater edible catfish of the region, are the important organs adopted chiefly for aerial respiration when the fish are under aquatic stress. The dendritic organs are the accessory respiratory organs and are present in suprabranchial chamber and are equally exposed along with the gills, the main respiratory organs to water-born toxicants including the arsenic. Live and healthy male and female C. batrachus L. (length 15 ± 1cm and weight 45 ± 5g) which were belonging to single population were exposed to 1 ppm sublethal concentration (1/10th of LC50 for 96h) of sodium arsenate heptahydrate (Na2HAsO4.7H2O) for 90 days. The 90 days arsenic exposed fish were returned to plain tap water again for 90 days to study the effects of withdrawal of arsenic stress. The fish were cold anaesthetized and dendritic organs were isolated and analysed histopathologically and histochemically after different periods of exposure and withdrawal of arsenic stress. Following exposure, blood capillaries of the secondary lamellae of dendritic organs showed extensive congestion followed by wear and tear. The ladder like arrangement of blood channels and supporting pillar cells gets dismantled and haemorrhages regularly took place in the dendritic organs. The density of red blood cells in subepithelial blood vessels of dendritic organs decreased. The staining property and density and area occupancy of mucous cells showed extensive periodic fluctuation showing more affinity for acidic glycoproteins containing sulphate and carboxylic groups. The density and area occupancy of mucous cells however decreased significantly (P < 0.05 and P < 0.01) at all stages of exposures of arsenic salt. Following withdrawal of arsenic stress, significant but incomplete recovery took place. The dendritic organs continued to show mucous cells hyperplasia. The density and staining properties of the mucous cells continued to remain altered.

Keywords: sodium arsenate, dendritic organs, catfish, histopathology, recovery.