Structure and function of the fibrillar coat of Leptorhynchoides thecatus eggs.

Leptorhynchoides thecatus eggs in fish feces were discovered to lack a thin, outer membrane present on eggs removed from body cavities of freashly collected worms; and to possess external structures which, with a light microscope, appeared as numerous fibrils. Scanning electron microscopy revealed to fibrils to be portions of a broad band of unwound fibrillar coat exposed after loss of the outer membrane. Fibrillar bands can entabgle in filamentous algae, anchoring eggs at the feeding sites of amphipod intermediate hosts. Amphipods fed in containers of algae over which eggs with exposed fibrillar bands had been added developed a significantly greater prevalence and intensity of acanthocephalan infection than did those fed in containers to which eggs had been added before the algae.