Primitive Toll signalling: bugs, flies, worms and man

A current area of interplay between immunologists, geneticists and developm ental biologists concerns how Toll receptors assumed their dual roles in pa thogen recognition end insect embryo patterning. The development of mechani sms that recognize and control infectious pathogens has been essential for the survival of metazoan organisms, Here, Padraic Fallen and colleagues con sider the insights that might be gained from using nematodes to study immun e signalling pathways.