  In this article we examine the formation of cylindrical neckpinch
singularities in Ricci flow in compact manifolds. Rigorous examples of
neckpinch sigularity for rotationally symmetric initial data were first
constructed by Angenent and Knopf, and examples with given asymptotic behaviour
were constructed by them and Isenberg. Here we discuss the asymptotic behavior
of the flow under Type-I assumption for general symmetric initial data, and
show the previously constructed asymptotic profiles and are the only
possibilities.
