Protective and recovery effects of edta on the toxicity of cadmium which leads to histopathological changes in Lymnaea stagnalis Linnaeus, 1758 (Gastropoda: Pulmonata)

Among the heavy metals cadmium (Cd) is the second on account of toxic after mercury. Such a study was decided for determine the effects of its toxicity on living organisms. For this experimental work; control, 63.4 ? g/l, 31.7 ? g/l, 15.85 ? g/l and 7.92 ? g/l Cd concentrations was chosen to be as five groups. In our study, 28-day Cd application process was followed by EDTA application for 28-day recovery period.The snails were dissected and foot, mantle and hepatopancreas tissue samples were taken in 7, 14, 21 and 28 days during Cd application and in 14 and 28 days in recovery periods for histopathological studies and chemical analysis.At the end of Cd application increase were seen in the number of mukosit, pigment and protein cells and lipid vacuoles with desquamation in the epithelium in the foot. Necrotic structures such as atrophy in muscle fibrils, pycnotic cell and cell with dual-core were detected. In mantle, atrophy in muscle fibrils, connective tissue cells and increase in the lipid vacuoles was observed. Also, desquamation in the epithelium has occurred. Due to expansion of hemolymphatic areas and spaces between tubules, increase in the lipid vacuoles and amoebocyte was observed in the hepatopancreas. Desquamation in the epithelium and vacuolation in tubules has occurred. Severity of the lesions has showed increase depending on the time progress and increasing in Cd concentrations. Most of the changes were reversible. However, histopathological lesions, slightly, still have been found after the recovery period. The obtained histopathological findings have been interpreted and photographs were taken.For chemical analysis of Cd in each tissue, the level of cadmium in the tissues was measured with Inductively Coupled Plasma - Emission Spectroscopy (ICP-OES). As a result of measurements, most of accumulation of Cd was detected in the hepatopancreas, then in the foot, and at least in the mantle. Cd levels in the tissues were decreased in specific rates at the end of recovery period.