And eventually what happens is this basically forms a closure and this also forms a closure. And so this is basically shut close. So following birth, there is a reversal of the pressure differential. That is, the pressure in the left atrium is greater, becomes greater than the pressure in the right atrium. And this causes the septum premium to push against the septum sequandum which closes the forayman O'Valley. And this usually takes place within minutes following birth.