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International Journal of Zoology
Volume 2009, Article ID 218197, 13 pages
http://dx.doi.org/10.1155/2009/218197
Review Article

Coelomocytes: Biology and Possible Immune Functions in Invertebrates with Special Remarks on Nematodes

Nematode Research Laboratory, Department of Zoology, Aligarh Muslim University, Aligarh 202002, India

Received 4 June 2008; Revised 22 September 2008; Accepted 6 November 2008

Academic Editor: Gregory Demas

Copyright © 2009 Qudsia Tahseen. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

All metazoans are exposed to a wide range of microbes and have evolved complex immune defenses used to repel infectious agents. Coelomocytes play a key role in the defense reactions of most invertebrates. They are involved in important immune functions, such as phagocytosis, encapsulation, graft rejection, and inflammation, as well as the synthesis and secretion of several humoral factors especially in annelids and echinoderms. Coelomocytes in nematodes are variable in shapes from round, ovoid, cuboidal, and spindle-shaped to stellate or branched cells that are found usually at fixed positions in the pseudocoelom. Their number usually varies from 2 to 6. The model nematode, C. elegans lacks an adaptive immune system and the coelomocytes are capable of endocytosis, but their involvement in phagocytosis of bacteria seems unlikely. The aim of this review is to evaluate current knowledge on coelomocytes of invertebrates with special reference to nematodes. The morphology and structure of these coelomocytes are discussed along with their origin. Their relative positions and diversity in different nematode groups have also been discussed and illustrated.