Noun
A transparent, extensible membrane of extreme tenuity, which forms the innermost coating of grains of pollen.
Source: Webster's dictionaryThe vegetative and generative cells are surrounded by a thin delicate wall of unaltered cellulose called the endospore or intine, and a tough resistant outer cuticularized wall composed largely of sporopollenin called the exospore or exine. Source: Internet
The callose wall is broken down by an enzyme called callase and the freed pollen grains grow in size and develop their characteristic shape and form a resistant outer wall called the exine and an inner wall called the intine. Source: Internet
These two layers are the tectum and the foot layer, which is just above the intine. Source: Internet