Histopathological study
At the end of 2 months, 5 snails were removed from each contaminated
sediment and control group. After the removal of the shells, snail organs (gill,
digestive tract and digestive gland) were fixed in Bouin’s solution overnight (for
24 h). Samples were washed with 70% alcohol, dehydrated through a graded series
of ethanols (70%, 80%, 95% and 100%), cleared in dioxan, and embedded in paraffin
wax. They were cut into sections of 5 mm thickness by a rotary microtome. The
sections were stained with periodic-acid-Schiff (PAS) and observed for histopathological
changes in gills, digestive tracts and digestive glands using a
compound light microscope (Olympus CH40); digital images were captured with
an Olympus (model DP12-2) digital camera.