The key difference between synergid and egg cell is that the synergid cell is one of the two cells that accompanies the egg cell while the egg cell is the female gamete or the female germ cell of angiosperms.
The flower is the reproductive structure of flowering plants. Within the flower, male and female reproductive structures are present. The gynoecium is the female reproductive structure, and it consists of the stigma, style and ovary. Inside the ovary, female gametophyte is present and it is also known as embryo sac or megagametophyte. Embryo sac contains the female gamete or the egg cell of angiosperms. Around the egg cell, several other cells can be found. Among those, two synergid cells accompany the egg cell.
CONTENTS
1. Overview and Key Difference
2. What is Synergid Cell
3. What is Egg Cell
4. Similarities Between Synergid and Egg Cell
5. Side by Side Comparison – Synergid vs Egg Cell in Tabular Form
6. Summary
What is Synergid Cell?
Embryo sac of angiosperms has four types of cells namely antipodal cells, synergid cells, central cell and egg cell. There are two synergid cells inside the embryo sac. They are the cells that accompany and support the egg cell. They locate with the egg cell. The term ‘synergid’ refers to ‘working together’. Hence two synergid cells work together with the egg cell during the fusion of egg cell and sperm cell. Furthermore, synergids provide protection and nutrients to the egg cells.
Figure 01: Synergid Cells inside the Embryo Sac
Once pollination completes, the pollen tube develops on the stigma. Synergid cells in the embryo sac produce attractants and guide the pollen tube towards the egg cells. Hence, a pollen tube grows within the stele towards the egg cell of the embryo sac. The pollen tube grows into one of the two synergid cells. Then after, the pollen tube stops its growth and ruptures to release two sperm cells. Synergid cell drives a sperm cell towards the egg cell for syngamy. Then the synergid cell degenerates. This reflects the importance of the synergid cells for successful fertilization.
What is Egg Cell?
Egg cell is the female gamete. It is also known as the female germ cell. In angiosperms, egg cell locates inside the embryo sac. It accompanies two synergid cells that are working together. Egg cell unites with the male gamete (sperm cell) and completes the fertilization process. After this union, it becomes the seed of flowering plants.
Figure 02: Egg Cell
Moreover, egg cell is haploid, and it contains half of the chromosomes that possessed by other cells. When it fuses with male gamete, it will result in the diploid cell, which is known as the zygote, ultimately gives birth to a new plant.
What are the Similarities Between Synergid and Egg Cell?
- In angiosperms, synergid and egg cell locate inside the female gametophyte, which is the embryo sac.
- Synergid cells support egg cell to be fertilized with a sperm cell.
- Both are necessary for a successful fertilization process.
- Synergid and Egg Cell can be found in gynoecium.
What is the Difference Between Synergid and Egg Cell?
Synergid and egg cell are two types of cells in the female angiosperm gametophyte. Two synergid cells accompany the egg cell and work together with the it for the successful fertilization. Egg cell is the female germ cell, and it fuses with the male germ cell and produces a diploid zygote. Whereas the synergid cells help the egg cells by providing protection as well as nutrients. This is the key difference between synergid and egg cell.
The below infographic presents more details on the difference between synergid and egg cell in tabular form.
Summary – Synergid vs Egg Cell
There are two synergid cells inside the embryo sac while there is one egg cell. Synergid cells are the supportive cells which accompany the egg cell. Egg cell is the female gamete which unites with a sperm cell or a male gamete during the sexual reproduction of angiosperms. Synergids guide the pollen tube that carries sperm cells to grow towards the egg cell for the fertilization. Furthermore, synergids provide protection as well as nutrients to egg cell. This is the difference between synergid and egg cell.
Reference:
1.Higashiyama, T. “The Synergid Cell: Attractor and Acceptor of the Pollen Tube for Double Fertilization.” SpringerLink, Springer, Dordrecht. Available here
2.Eckardt, Nancy A. “Elucidating the Function of Synergid Cells: A Regulatory Role for MYB98.”Plant Cell, American Society of Plant Biologists, 1 Aug. 2007. Available here
Image Courtesy:
1.”Embryosac-en”By Lokal_Profil, (CC BY-SA 2.5) via Commons Wikimedia
2.”Figure 32 02 07″By CNX OpenStax (CC BY 4.0) via Commons Wikimedia