Q.What is meant by monosporic development of female gametophyte?
You're viewing a preview — the full solution, concept, methods & PYQ mapping are locked.
Start your 14-day free trial to unlock the full solution →Monosporic development of the female gametophyte refers to the formation of the embryo sac from a single functional megaspore.
In flowering plants, the female gametophyte, also known as the embryo sac, develops within the ovule. This development begins with a specialized cell called the megaspore mother cell (MMC), located in the nucellus region of the ovule. The megaspore mother cell is diploid (2n) and undergoes meiosis, a reductional division, to produce four haploid (n) megaspores.
The term "monosporic development" specifically describes the most common pathway for the formation of the female gametophyte. In this type of development, out of the four megaspores produced by meiosis, only one remains functional. Typically, this is the megaspore located at the chalazal end of the ovule, while the other three megaspores, usually towards the micropylar end, degenerate and perish.
The degeneration of three megaspores ensures that the single functional megaspore receives ample nutrients for its subsequent development into the embryo sac.
The single functional megaspore then enlarges significantly and undergoes a series of mitotic divisions. These mitotic divisions are initially free nuclear, meaning the nucleus divides repeatedly without the immediate formation of cell walls.
Typically, three successive mitotic divisions occur:
- The nucleus of the functional megaspore divides once to form two nuclei.
- These two nuclei move to opposite poles of the megaspore.
- Each of these two nuclei divides again, resulting in four nuclei (two at each pole).
- Finally, these four nuclei divide one more time, leading to an 8-nucleate stage (four nuclei at each pole).
After the 8-nucleate stage, cell walls are laid down, organizing the nuclei into distinct cells to form the mature embryo sac. This mature female gametophyte is typically a 7-celled, 8-nucleate structure: …
Unlock everything free for 14 days
- Full step-by-step solutions
- Concept-first explanations
- Methods, shortcuts & mistakes
- PYQ mapping + timed mock tests
Full access for 14 days. No credit card required.