The localization of worm antigen of Neodiplostomum seoulense was examined by immuno-electronmicroscopic observation. Not only the immunized serum of mice with crude worm extract of N. seoulense but also serum of infected mouse were reacted to the worm section. Using immunized serum as primary antibody, the gold particles were deposited on the rough endoplasmic reticulum of the cell of tribocytic organ, spermatozoa in the seminal vesicle, microvilli of the caecum and vitelline follicle. Using infected serum, gold particles were deposited only on the vitelline follicle prominently. This finding suggested that the tribocytic organ, seminal vesicle, caeca and vitelline follicles may play a role of antigen to immunized serum with crude worm extract of N. seoulense, whereas the vitelline follicle, to the infected serum.
