7 Celled 8 Nucleate Structure Ovule With Labelled Diagram

                       Process Of Megasporogenesis In Angiosperm

In the previous blog, we had talked about how Archesporial cell meiotically divides and form four haploid cell arranged in a linear manner.

 Now out of the four cells, only one is functional while the other three degenerate. This is known as monosporic development.  One functional megaspore will give rise to the female gametophyte.
 Now let's go in more detail.

The functional megaspore will now start to divide mitotically and form two nuclei which start to move in the opposite direction where they form two nucleate embryo sac. Now the resulted two nuclei again divide by mitotic division and in this way, there is a formation of four nucleate and on further it divides more to becomes 8 nucleate of the embryo sac.

These 8 nucleate cells arranged in so well manner to form female gametophyte. Out of the eight nuclei, six nuclei covered by a cell wall and organized to form cells and the remaining two are known as Polar nuclei, situated below the egg apparatus in the central cell.

Now out of the six-cell, three cells organized in the embryo sac to form egg apparatus in the micropyle region of the ovule. This egg apparatus itself consists of two synergid cells and one egg cell. The synergid cell is consists of filiform apparatus, a finger-like projection help in inserting male gamete through a pollen tube.
At the Chalazal end, the three cells combine to form Antipodal cells, provide nutrition to the cell.
As I mentioned on the top that central cells have two polar nuclei, that's why after maturity this embryo sac has 8 nucleate, 7 celled structure.