Immunoelectron microscopic study of Actinomyces colony in odontogenic periapical infection.

A periapical Actinomyces colony was studied by immunoelectron microscopy with a specific antiserum against Actinomyces israelii. Positive as well as some negative micro-organisms were seen within the colony. Reacting antigens were localized in the cytoplasm and the cell wall of the bacteria, which suggests that more than one antigen is involved in the reactions with the present antiserum. The ultrastructural results confirmed the applicability of the peroxidase method with Actinomyces antiserum in paraffin sections for diagnostic purposes.