Resistance of Biomphalaria alexandrina to Schistosoma mansoni and Bulinus truncatus to Schistosoma haematobium Correlates with Unsaturated Fatty Acid Levels in the Snail Soft Tissue

Figure 3

Histological transverse sections of B. alexandrina snails showing cephalopodal tissue. (a, b) are of naïve snails maintained on algae (a) and lettuce (b). (c, d) are of infected snails maintained on algae and lettuce, respectively, showing live S. mansoni mother sporocysts with normal development pattern; some of them contain single sporocyst cluster (thin arrow), and others contain multiple sporocyst clusters (thick arrow). (e, f) are of snails that resisted infection. Cephalopodal tissue is seen showing dead sporocyst (thin arrow) surrounded by granuloma-like structure consisting of layers of flattened hemocytes followed by concentric layer of fibroblasts (thick arrow) (e). The mantle collar region shows the sporocysts losing their identical cluster-like shape and presence of germinal cells lacking nucleoli. The size of the vacant space (thin arrow) is wider than in normal sporocysts. Note, presence of fibroblast lamination (thick arrow) surrounding the sporocysts’ tegument (f).

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