Q. Filiform apparatus
Solution:
Megaspore Mother Cell, after meiotic division forms four Megaspore Tetrad (n). From these four cells, the cell towards the Micropylar end becomes functional Megaspore and other three degenerates. This is called Monosporic Embryo sac development.
The functional megaspore undergoes three successive mitotic divisions and forms an Embryo sac or the Female Gametophyte with 8 nuclei.
Once all three mitosis are over, the wall formation takes place. Three cells are aligned towards the Chalazal end of the Ovule which forms the Antipodals (n). Two central nuclei fuse to form Polar Nuclei (2n). Egg cell (n) along with two Synergids (n) move towards the Micropylar end.
Synergid cells possess some finger-like projections, called Filiform apparatus. These are specialised cellular thickenings present towards the micropyle. They help in
1. Guiding the pollen tube during entry of pollen tube to embryo sac.
2. Help in releasing the male gametes during syngamy.
3. They help in short distance movement of male gametes within the embryo sac.
The functional megaspore undergoes three successive mitotic divisions and forms an Embryo sac or the Female Gametophyte with 8 nuclei.
Once all three mitosis are over, the wall formation takes place. Three cells are aligned towards the Chalazal end of the Ovule which forms the Antipodals (n). Two central nuclei fuse to form Polar Nuclei (2n). Egg cell (n) along with two Synergids (n) move towards the Micropylar end.
Synergid cells possess some finger-like projections, called Filiform apparatus. These are specialised cellular thickenings present towards the micropyle. They help in
1. Guiding the pollen tube during entry of pollen tube to embryo sac.
2. Help in releasing the male gametes during syngamy.
3. They help in short distance movement of male gametes within the embryo sac.