The wall of the ducts is formed by a lining epithelium that forms a small tube with a central lumen. The epithelium that forms the duct is initially of the simple cubic type. If the gland is small and the duct is short, it maintains this structure throughout its course, subjected to a high degree of pressure.
These ducts have from more complex glands the duct epithelium ends up becoming simple prismatic and may even become stratified. In this case, the tissues have stratified layering
There are far to many variables to make a true accurate answer, this is coming from a medical responder BUT lots of texts say about 120 min....but that's very much debatable
