What effect did the Reformation have inside the Catholic Church?

I confess my knowledge of church history branches at about the Reformation. I know a quite a bit about Catholicism today, and I have an idea of what it was before the Reformation. These are not at all the same thing. What changes inside the Roman Catholic church, either in practice or doctrine, are directly attributed to the events of the Reformation? How soon after the reformation was this change visible/acknowledged?