Experimental oral foreign body reactions: vegetable materials. Foreign bodies and tissue reactions to foreign materials are commonly encountered in the oral cavity. Exogenous materials most commonly causing foreign body reactions are metallic in origin (usually amalgam). Of the nonmetallic materials seen during biopsies, suture materials and vegetable matter are most often observed. Since many foodstuff foreign materials are unidentifiable histologically, common vegetables were experimentally implanted subcutaneously in rats to assess local host responses and to characterize the nature of these materials microscopically. The histologic characteristics of these vegetable foreign body reactions are detailed herein. The implanted materials correspond to reactions seen in human subjects. 