Microsporogenesis :
(a) The interior of the microsporangium is filled with sporogenous cells. These sporogenous cells divide meotically to form microspore tetrads.
(b) So, the cells of sporogenous tissue are called pollen or microspore mother cell (PMC) because they undergo meiosesto produce pollen grains.
( c) The process of formation of micro spore from a pollen mother cell through meiosis is called microsporogenesis.
(e) when the anther matures and dehydrates, the microspores differentiate into pollen grains.
Pollen grains
(a) They develop from PMC due to meiotic division.
(b) They represent the male gametophyte.
(c) Pollen grainf- are generally spherical in outline.
(d) They possess two prominent layered walls.
(e) The outer layer is called exine and the inner layer is called in tine.
(f) The exine is the outermost hard layer chemically composed of sporopollenin which is one of the most resistant organic material.
(g) The exine has prominent aperture formed due to absence of sporopollenin through which the pollen tube develqps called germ pore.
(h) The innermost thin layer chemically composed of cellulose and pectin is called intine.
(i) The newly differentiated pollen grain has central nucleus and dense cytoplasm.
(j) Vacuoles develop thereby pushing the nucleus towards the periphery.
(k) The protoplast then divides mitotically forming two unequal cells-bigger vegetative which is rich in food reserve and smaller generative cell with dense cytoplasm and a nucleus.
