  During germinal center reactions the appearance of two specific zones is
observed: the dark and the light zone. Up to now, the origin and function of
these zones are poorly understood. In the framework of a stochastic and
discrete model several possible pathways of zone development during germinal
center reactions are investigated. The importance of the zones in the germinal
center for affinity maturation, i.e. the process of antibody optimization is
discussed.
