The pollen grains consists two layers; the outer exine
and the inner intine.
The intine is a uniform thin laye
r made up of pectolase which is destroyed during the acetolysis. The exine
is divided into two layers the outer sculptured sexine
and the inner non-sculptured laye
r known as the nexine. The exine
which is capable of resistant to physical and biological degradation and acetolysis.
This helps the pollen grains to be preserved for long periods
of time in fossil deposites.