Development of Female Gametophyte, Definition, Stages, and Functions

Development of female gametophyte  is a vital topic in plant reproduction and has significant importance in biology. It helps explain key processes like fertilization and double fertilization. The female gametophyte, also called the embryo sac, is a critical structure in the reproduction of flowering plants. It is a haploid structure formed inside the ovule, located within the ovary of a flower. This topic is vital for understanding plant reproduction and is important for the  NEET Exam .

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Development of Female Gametophyte

Definition of Gametophyte

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Stages in the Development of Female Gametophyte

Megasporogenesis

• Initiation in the Ovule : The development begins with the differentiation of a single cell in the nucellus called the megaspore mother cell (MMC). The MMC is diploid (2n) and undergoes meiosis.
• Formation of Megaspores : Meiosis in the MMC results in the production of four haploid (n) megaspores arranged in a linear tetrad. Out of these four, only one megaspore located at the chalazal end becomes functional. The other three degenerate and disintegrate.

Megagametogenesis

• Mitotic Divisions : The functional megaspore undergoes three rounds of mitotic division, resulting in an eight-nucleate structure.
• Organization into Cells : These eight nuclei are arranged in specific locations:
  • Three nuclei move to the micropylar end to form the egg apparatus, consisting of one egg cell and two synergids.
  • Three nuclei move to the chalazal end, forming antipodal cells.
  • Two nuclei remain in the center of the embryo sac and form the polar nuclei, which later fuse to form a diploid secondary nucleus.
• Final Structure : The mature embryo sac has seven cells (three antipodal cells, two synergids, one egg cell, and one central cell) but contains eight nuclei.

Functions of Female Gametophyte

• The egg cell within the gametophyte acts as the female gamete.
• The synergids guide the pollen tube, ensuring successful fertilization by directing the male gamete to the egg cell.
• The central cell's secondary nucleus fuses with one male gamete to form the endosperm, which provides nourishment to the developing embryo.
• The female gametophyte provides the environment necessary for the initial stages of embryogenesis.

MCQs of  Development of Female Gametophyte

Q1. An ovule generally has a single embryo sac formed from a megaspore through;

1. reduction divisions.
2. mitotic divisions.
3. mitotic division followed by meiotic division.
4. meiotic divisions followed by mitotic division.

Q2. Functional megaspore in an angiosperm develops into:

1. Ovule
2. Endosperm
3. Embryo sac
4. Embryo

Q3. The functional megaspore is referred to as;

1. megasporangium
2. female gamete
3. ovule
4. embryo sac

Answers of MCQs of Development of Female Gametophyte