Effects of excretory-secretory products of Echinostoma paraensei larvae on the hematopoietic organ of M-line Biomphalaria glabrata snails.

Responses of the hematopoietic organ (HO) in Biomphalaria glabrata snails to extracts and excretory-secretory (E-S) products of Echinostoma paraensei larvae were studied to understand the HO-activating mechanism. M-line B. glabrata snails were injected with materials from E. paraensei larvae, and the size of the HO was ascertained in histological sections. The size of HO in snails injected with extracts and E-S products from sporocysts and rediae was significantly larger than that in snails injected with culture medium. E-S products of sporocysts were fractionated using ultrafiltration membranes, polyacrylamide gel electrophoresis, and electrophoretic elution. Examination of fractionated E-S products of sporocysts revealed that specific components of E-S products were responsible for HO-stimulating activity.