Sexual Reproduction in Flowering Plants Test - 9

Megaspore mother cell are diploid, which generally undergo reduction division to produce megaspore but in some plants diploid megaspore mother cell directly produce diploid embryo sac this condition is called diplospory

The embryo sac is 8 nucleate, 7 celled structure. The three at micropylar ends are called egg Synergids and three at chalazal end are called antipodal cell. The remaining two at center forms the polar bodies.

Each microspore mother cell produces four pollen grains by reduction division. Hence to produce 64 pollen grains 16 meiotic or reduction division is required.

Filiform apparatus is finger-like projection attached with egg apparatus. This apparatus guide the pollen tube carrying male gametes for facilitating Syngamy.

Each Sporogenous cell under meiotic division to form tetrad of megaspores. The three megaspores degenerate and only one megaspore develops into embryo sac or female gametophyte.

The process of male gamete formation involves following events in succession as Sporogenous tissue, microspore mother cell, microspore formation and pollen grain that finally produce two male gametes.

The anther is a tetragonal structure consisting of four microsporangia located at the corners, two in each lobe. Microsporangium develops to form pollen sacs inside which pollen grains are formed.

Microsporangium is surrounded by four wall layers. The innermost layer is tapetum. Tapetum nourishes the developing pollens. The three outer walls provide protection and help in dehiscence of anther to release pollen grains.

The megaspore mother cell undergoes meiotic division to form four megaspores. One megaspore becomes functional and other three degenerate. The functional megaspore develops into female gametophyte.