The tapetum is a layer of cells that is found within the pollen sac, a nutritive tissue within the sporangium, particularly within the anther. Tapetum is important for the development of pollen grains. The cells are usually bigger and normally have 2 nuclei per cell, i.e. a syncytium. It helps in pollenwall formation, transportation of nutrients to inner side of anther, synthesis of callase enzyme for separation of microspore tetrads. Orbicules originate as small lipid droplets, called pro-orbicules, in the rough endoplasmatic reticulum of the tapetum.