  In the late 1960s the discovery of the Crab pulsar in its associated
supernova remnant, launched a new field in supernova remnant research: the
study of pulsar-driven or plerionic supernova remnants. In these type of
remnants, the relativistic wind emitted by the pulsar, blows a pulsar wind
nebula into the interior of its supernova remnant. Now, more then forty years
after the discovery of the Crab pulsar, there are more then fifty plerionic
supernova remnants known, due to the ever-increasing capacity of observational
facilities. I will review our current understanding of the different
evolutionary stages of a pulsar wind nebula as it is interacting with its
associated supernova remnant.Therefore I will discuss both analytical and more
recent numerical (M)HD models.The four main stages of a pulsar wind nebula are:
the supersonic expansion stage, the reverse shock interaction stage, the
subsonic expansion stage and ultimatelythe stage when the head of the bubble is
bounded by a bow shock, due to the supersonic motion of the pulsar. Ultimately
this pulsar wind nebula bow shock will break through its associated remnant,
after which the pulsar-powered bow shock will interact directly with the
interstellar medium. I will discuss recent numerical models from these type of
pulsar wind nebulae and their morphology.
