الفهرس 
Histological structure of egg massesOnly 14 pages are availabe for public view
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Abstract
Normal development of Biomphalaria alexandrina snails was studied and the time course of stages was determined. In this study, two important drugs for human were used (colchicine and niclosamide). The present study was planned to follow up the teratogenic potency of both drugs on developmental stages of B. alexandrina.The results showed that exposure of adult snails to LC10 of both drugs for 24 hrs / week for 4 weeks markedly reduced their reproductive rate. As well, histopathological damage in the treated egg masses containing fertilized egg was occurred. Both drugs caused degeneration of gelatinous matrix of tunica interna and tunica externa, appearance of deep colored unknown aggregated granules of various sizes and appearance of numerous vacuoles in the cytoplasm of the fertilized egg referring to beginning of necrosis. Niclosamide was largely destroyed the egg capsule and fertilized eggs than colchicine.