What role pressures play to determine the final end-state of   gravitational collapse?
  We examine here in what way the pressures affect the final fate of a continual gravitational collapse. It is shown that the presence of a non-vanishing pressure gradient in the collapsing cloud determines directly the epoch of formation of trapped surfaces and the apparent horizon, thus changing the causal structure in the vicinity of singularity. 
Rituparno Goswami, Pankaj S Joshi