The female gametophyte of flowering plants is called the
The female gametophyte of flowering plants is called the embryo sac
The female gametophyte of flowering plants is called the embryo sac. The embryo sac is a multicellular structure that develops within the ovule of a flower. It is the site of fertilization and subsequent embryo development.
The embryo sac is formed from a single diploid cell called the megaspore mother cell, located within the ovary of the flower. Through a process called megasporogenesis, the megaspore mother cell undergoes meiosis to produce four haploid cells called megaspores. However, only one megaspore typically survives and develops further, while the remaining three degenerate.
The surviving megaspore undergoes three rounds of mitosis, resulting in the formation of eight haploid nuclei. These nuclei become enclosed within a cell membrane, creating seven cells with different functions. These cells are:
1. Three antipodal cells: Positioned at the opposite end of the embryo sac from the micropyle (the opening of the ovule), these cells are usually not well-defined in their function.
2. Two synergids: These cells are located near the micropyle and have a role in guiding the pollen tube to the embryo sac during fertilization.
3. One central cell: This cell contains two haploid nuclei and is involved in the formation of the endosperm, a nutritive tissue that supports the developing embryo.
4. One egg cell: This is the female gamete within the embryo sac and is involved in fertilization.
During fertilization, a pollen tube carrying two sperm cells enters the embryo sac. One sperm cell fuses with the egg cell, resulting in a diploid zygote, which develops into the embryo. The other sperm cell fuses with the two nuclei in the central cell, forming a triploid nucleus. This triploid nucleus undergoes several rounds of mitosis to form the endosperm, which provides nourishment to the developing embryo.
Overall, the embryo sac plays a vital role in the reproductive cycle of flowering plants by providing a specialized environment for fertilization and subsequent embryo development.
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