With a neat diagram explain the $7 -$ celled, $8 -$ nucleate nature of the female gametophyte.

Vedclass pdf generator app on play store
Vedclass iOS app on app store

The female gametophyte (embryo sac) develops from a single functional megaspore. This megaspore undergoes three successive mitotic divisions to form eight nucleate embryo sacs.

The first mitotic division in the megaspore forms two nuclei. One nucleus moves towards the micropylar end while the other nucleus moves towards the chalazal end. Then, these nuclei divide at their respective ends and redivide to form eight nucleate stages. As a result, there are four nuclei each at both the ends i.e., at the micropylar and the chalazal end in the embryo sac. At the micropylar end, out of the four nuclei only three differentiate into two synergids and one egg cell. Together they are known as the egg apparatus. Similarly, at the chalazal end, three out of four nuclei differentiates as antipodal cells. The remaining two cells (of the micropylar and the chalazal end) move towards the centre and are known as the polar nuclei, which are situated in a large central cell. Hence, at maturity, the female gametophyte appears as a $7 -$ celled structure, though it has $8 $ nucleate. (figure)

964-s6

Similar Questions

The germination of pollen grain results in the formation of

Which is not a part of pistle?

Megasporangium is equivalent to

  • [NEET 2013]

Persistent nucellus in the seed is known as

  • [NEET 2019]

'Cells in the micropylar region are called antipodal cell'