In this study, both digestive and hermaphrodite glands in Biomphalaria alexandrina snails were examined by light microscope (LM) and scanning electron microscopy (SEM) in a trial to clarify its immunological role as defense mechanism against the parasite infection. B. alexandrina snails used were exposed individually to Schistosoma mansoni miracidia; according to their response they were classified into infected snails (shed cercariae) and non-infected snails (failed to shed cercariae). Snails not exposed to S. mansoni miracidia used as control. LM showing great histological alteration in tissues of the both glands in infected snails, these changes represented by degenerated both oocyte and spermatocyte in hermaphrodite gland in addition to degenerated digestive gland while non-infected snails showing mild degenerated ova
with normal spermatocytes also degenerated miracidia inside granuloma like structure with concentric layers of fibroblast and haemocyte could be observed. By SEM we could detect extensively damaged and fibrosed non-motile cilia with exfoliation of tegumental surface in infected B.alexandrina while non-infected ones showing attached numerous cilia with some ballooning of the folds.