The lenticels are formed below the stomata which is developed along with the formation of the periderm. During the formation the substomatal parenchymatous cells becomes active and it then divides in different planes to form a mass of rounded cells. These cells then get enlarged, loose and light coloured. Then some loosely arranged cells are formed in the outer side by the activity of cork cambium instead of forming the cork cells. The loosely arranged cells and the cork cambium altogetherly is known as the complementary cells. The complemetary cells are oval in shape and is thin walled loosely arranged with large inter cellular spaces. The continued growth of these cells causes the rupturing of the epidermis and as a result the underlying tissue get exposed.