Adaptation of Haplobothrium globuliforme (Cestoda: Pseudophyllidea) to the intestinal architecture of the bowfin (Amia calva L).

Haplobothrium globuliforme maintains its position in the proximal mid-gut epithelium of Amia calva with the aid of tentacles, i.e., proboscides, everted from scolices of a primary strobila and craspedote proglottids of a secondary strobila. Weakly developed scolices of the secondary strobila appear to have little holdfast action, but the distinctly craspedote proglottids of these individuals project into the intestinal mucosa, altering the configuration of gut epithelial cells and pushing the tapeworm deeper into mucosal crypts. The basement membrane underlying the epithelium appears to act as a barrier that prevents tapeworms from penetrating into the deeper tissue layers of the lamina propria, muscularis mucosa, or submucosa. Scolex tegument modification occurs at the point of contact with host basement membrane. A mild background infiltrate of lymphocytes and granulocytes was evident adjacent to the scolex and proglottid tegument. There was no evidence of blood vessel proliferation, edema, mast cell degranulation, eosinophilia, or subsequent collagen formation associated with tapeworm activity.