The egg apparatus is a group of three specialized cells found at the micropylar end of the embryo sac in flowering plants (angiosperms). These cells play a crucial role in fertilization.
Composition of the Egg Apparatus
The egg apparatus consists of the following cells:
- One egg cell: This is the female gamete that, upon fertilization, develops into the embryo.
- Two synergids: These are two specialized cells that flank the egg cell. Synergids play a crucial role in pollen tube guidance and pollen tube reception, helping the sperm cells reach the egg cell.
| Cell Type | Function |
|---|---|
| Egg Cell | Develops into the embryo after fertilization. |
| Synergids | Guide the pollen tube and facilitate sperm cell entry during fertilization. |
Formation of the Egg Apparatus
The egg apparatus is formed through the following process:
- The process begins with a megaspore undergoing mitotic divisions.
- These mitotic divisions result in the formation of the embryo sac, which contains seven cells in many angiosperms.
- Within the embryo sac, at the micropylar end (the end where the pollen tube enters), three cells differentiate to form the egg apparatus – one egg cell and two synergids.
Importance of the Egg Apparatus
- Fertilization: The egg cell within the egg apparatus is the primary recipient of the male gamete (sperm cell) during fertilization, initiating the development of a new plant embryo.
- Pollen Tube Guidance: The synergid cells secrete chemical signals that guide the pollen tube towards the embryo sac, ensuring successful delivery of sperm cells.
- Sperm Reception: Synergids also play a role in accepting the sperm cells from the pollen tube, facilitating the fusion of gametes.
Conclusion
The egg apparatus is vital for sexual reproduction in flowering plants. It comprises an egg cell and two synergid cells, located within the embryo sac, all working together to achieve successful fertilization and embryo development.
