REMEDIATION OF CADMIUM TOXICITY CAUSED BY EDTA AND EICHHORNIA CRASSIPES IN THE DIFFERENT REGIONS OF THE ALIMENTARY CANAL OF ANABAS TESTUDINEUS (BLOCH): A SCANNING ELECTRON MICROSCOPIC STUDY

摘要

Remediation of heavy metals in aquatic ecosystem by EDTA or wetland plants like water hyacinth, Eichhornia crassipes is an important in the field of industrial toxicology. The present investigation demonstrates the comparative study of remediation byEDTA and Eichhornia occurred in the different regions of the alimentary canal like buccopharynx, oesophagus, stomach, intestine and rectum of an air-breathing teleost, Anabas testudineus being exposed by cadmium, cadmium - EDTA and cadmium-Eichhornia inthe laboratory conditions. The mucosal surface of the buccopharynx and oesophagus are provided with number of prominent folds comprising of pentagonal and/ or hexagonal stratified epithelial cells which are embraced with concentric microridges and double-ridged structures inbetween neighbouring cells. Treatment with Cd-EDTA and Cd-Eichhornia reveal that in both the cases stratified epithelial cells depict reduced lesions and less damage in microridge structures, particularly in Cd-Eichhornia treated condition the double-ridge remain intact as compared with Cd-EDTA treated tissues. Excessive mucous cells activity due to cadmium-toxication is suppressed by the plant incorporation. In stomach, cadmium toxicity causes prominent alterations in the mucosal folds, necrosis of gastric epithelium and vigorous secretion, but due to Cd-EDTA treatment the magnitude of necrosis in the SEC is very low and in case of Cd-Eichhornia treated condition gastric folds are of normal pattern of network, cellular lesions inthe columnar epithelial cells are very low and very slight obliteration in the microvilli. The severe necrosis in the absorptive CEC of the intestine along with deterioration of microvilli is prominently reflecting the cadmium toxicity. In Cd-EDTA condition, damage in microvilli is rarely observed; in Cd-Eichhornia treated condition the orientation of CEC and its microvilli is comparable to control condition. Rectal mucosal folds are highly damaged showing serious necrosis in the columnar epithelial cells due to cadmium toxicity. But in the Cd-EDTA and Cd-Eichhornia treated conditions the mucosal folds and microridges of the cells are almost intact and the changes are insignificant.