What is Egg Apparatus?
The egg apparatus is formed during the development of the embryo sac. The megaspore, which is the female gametophyte of the plant, undergoes three mitotic divisions to produce the seven-celled embryo sac. The egg apparatus is formed during the second mitotic division.
The egg apparatus is important for sexual reproduction in plants. The egg cell is fertilized by a pollen grain, and the resulting zygote develops into a new plant. The synergids and antipodal cells degenerate after fertilization.
Facts About Egg Apparatus:
Facts about the egg apparatus are as follows:
- It is found in all flowering plants.
- It is located at the micropylar end of the embryo sac.
- It is composed of three cells: the egg cell, the synergids, and the antipodal cells.
- The egg cell is the female gamete of the plant.
- The synergids are sterile cells that help guide the pollen tube to the egg cell.
- The antipodal cells are sterile cells that may have a role in preventing self-fertilization.
What Does Egg Apparatus Consist Of?
The egg apparatus consists of a group of three cells found at the micropylar end of a common angiosperm embryo sac. The three cells are:
- Egg cell: This is the female gamete, or sex cell, of the plant. It is haploid, meaning it contains half the number of chromosomes as the rest of the plant's cells.
- Synergids: These are two sterile cells that surround the egg cell. They are also haploid and have finger-like projections called filiform apparatuses. These projections are thought to help guide the pollen tube to the egg cell.
- Antipodal cells: These are three haploid cells that are located opposite the egg apparatus. They are thought to have a role in preventing self-fertilization.
Functions Of Egg Apparatus:
Here are some additional functions of the egg apparatus:
- Guide the pollen tube to the egg cell: The filiform apparatus of the synergids helps to guide the pollen tube to the egg cell. The pollen tube releases chemicals that dissolve the cell walls of the synergids, allowing them to enter the embryo sac.
- Provide nourishment for the developing embryo: The central cell produces endosperm, which provides nourishment for the developing embryo. The endosperm is a triploid tissue, meaning that it contains three sets of chromosomes.
- Regulate the development of the embryo and endosperm: The central cell also produces hormones that help to regulate the development of the embryo and endosperm. These hormones control the growth and division of the cells, as well as the synthesis of proteins and other nutrients.
What is Egg Apparatus ploidy?
The ploidy of the egg apparatus is (2n + 3n). This means that the egg cell and synergids are haploid (n), while the central cell is triploid (3n). Haploid cells contain one set of chromosomes, while diploid cells contain two sets of chromosomes. Triploid cells contain three sets of chromosomes. After fertilization, the haploid nucleus in the central cell fuses with one of the sperm nuclei from the pollen tube. This fusion creates a diploid nucleus, which then fuses with the other sperm nucleus. This fusion creates a triploid nucleus.
The triploid nucleus in the central cell then divides to form the endosperm, which is a tissue that provides nourishment for the developing embryo. The ploidy of the egg apparatus is important because it determines the ploidy of the endosperm. A triploid endosperm is necessary for the normal development of the embryo.
In some cases, the ploidy of the egg apparatus can be different. For example, in some species, the central cell may be tetraploid (four sets of chromosomes). In these cases, the endosperm will also be tetraploid. The ploidy of the egg apparatus is a complex and important topic in plant biology. It is still not fully understood how the ploidy of the egg apparatus is determined. However, research is ongoing to better understand this process.
Where is Egg Apparatus situated?
The egg apparatus is situated at the micropylar end of a common angiosperm embryo sac. The micropyle is the opening at the tip of the ovule, which is where the pollen tube enters. The egg apparatus is located just inside the micropyle, and it is made up of three cells: the egg cell, two synergids, and the central cell.
The egg cell is the female gamete, and it is the largest cell in the egg apparatus. The synergids are two smaller cells that surround the egg cell, and they have a specialized structure called the filiform apparatus. The filiform apparatus helps to guide the pollen tube to the egg cell. The central cell is a large cell that is located between the synergids and the egg cell. It is binucleate, meaning that it contains two nuclei.