Immune Responses in the Earthworm, Aporrectodea trapezoides (Annelida), Against Rhabditis pellio (Nematoda)

Abstract

Immune responses of earthworms to nematodes or other metazoan parasites have received little attention. While investigating the behavior of Rhabditis pellio in the earthworm, Apovreotodea trapezoides, Poinar and Thomas (1976) noted that most nematodes occurred in the bladders and tubules of the metanephridia. However, those that entered the coelom were promptly encapsulated and incorporated into “brown bodies.” These “brown bodies” not only contained nematodes but also protozoan cysts and other debris that occurred in the worm’s coelom. It was clear that the “brown bodies” constituted an immune response on the part of the worm which is probably typical for oligochaete annelids. The purpose of this investigation was to examine the ultrastructure of the “brown bodies” of A. trapezoides containing R. pellio.