ABSTRACT
This study was performed on albino mice infected with both Egyptian and Saudi Schistosoma mansoni strains to investigate the characteristic differences between them. It was found that at the 8th week post-infection, the highest amount of egg deposition and granuloma formation was present in the liver of infected mice with the Egyptian strain, while it was highest in the small intestine of those infected with the Saudi strain, followed by the liver and the large intestine. Although no prominent histopathologic differences were detected in the cellular and tissue reactions in the resulting granulomata surrounding eggs, yet marked differences were observed in the surface topography of the tegument and distribution of papillae, pattern of ridges, microvilli and spines of both strains. These differences were more pronounced in males