Question

Describe the process of microsporogenesis in Angiosperms with diagrams.

Hint:

Microsporogenesis produces four haploid microspores from one diploid microspore mother cell through meiosis, and each microspore forms a pollen grain that contains two cells: the vegetative and generative cells.

Answer 1

Microsporogenesis is the process by which microspores are formed from the microspore mother cells (or pollen mother cells) in the anthers of angiosperms (flowering plants). It is the first step in the formation of male gametes (pollen grains) that participate in fertilization. The process of microsporogenesis occurs in the following stages:
1. Formation of Microspore Mother Cells (PMC):
The anthers of a flower consist of four microsporangia. Each microsporangium contains diploid microspore mother cells (PMC). These cells are derived from the sporogenous tissue, which is composed of diploid cells.
2. Meiosis (Reduction Division):
Each microspore mother cell undergoes meiosis, a type of cell division that reduces the chromosome number by half. Meiosis consists of two divisions: - Meiosis I: The diploid PMC undergoes the first meiotic division, resulting in two haploid cells. - Meiosis II: The two haploid cells divide again, producing four haploid microspores. These microspores are the result of reduction division, and each contains a single set of chromosomes (n).
3. Formation of Microspores:
After meiosis, the four microspores are formed, each surrounded by a thin cell wall. These microspores are haploid, meaning they carry half the genetic material of the parent cell.
4. Development of Pollen Grain (Microgametogenesis):
The microspores then undergo mitotic divisions to form the pollen grains. Each microspore develops into a pollen grain, which consists of two cells: a large vegetative cell and a smaller generative cell. The vegetative cell forms the tube cell, which eventually forms the pollen tube during fertilization, and the generative cell divides further to form two male gametes (sperm cells).