The microfilariae of several genera of filariae are enclosed by a flex
ible, bag-like structure, the 'microfilarial sheath: which is synthesi
zed in a co-ordinated way by both the embryo and the uterine epitheliu
m. In this article, Horst Zahner, Gerd Hobom and Stephan Stirm conside
r its structure and composition, and its role in the survival strategy
of the parasites by evading the host's immune reaction.