Explain the role of the tapetum in the formation of the pollen grain wall.

(N/A) The tapetum is the innermost layer of the microsporangium. It plays a crucial role in the development of pollen grains by providing nourishment. During microsporogenesis,tapetal cells secrete various enzymes,hormones,amino acids,and other essential nutrients. Most importantly,the tapetum is responsible for the synthesis and deposition of $sporopollenin$,which forms the outer layer of the pollen grain known as the $exine$.