What is Microsporogenesis?

Microsporogenesis is the formation of microspores inside a microsporangium (or pollen sac) by meiotic or reduction division. The formation of pollen grains from the microspores is termed microgametogenesis.

Formation of Microspores

• The developing anther consists of two types of cells: reproductive and non-reproductive cells.
• The diploid cells, or the reproductive cells in the sporogenous tissue of microsporangium called meiocytes or pollen mother cells, divide by meiosis to produce four haploid microspores.
• The first reduction division gives two nuclei, and the second division finally gives a tetrad of microspores.
• The non-reproductive cells form the anther tissue layers including epidermal, tapetal and cortical layers.
• The tapetal layer functions as a nutritive tissue for the developing anther.

Formation of Pollen Grains

• The formation of pollen grains from the microspores is termed microgametogenesis.
• It begins with the expansion of the microspore and the formation of a large vacuole.
• It is followed by displacement of the microspore nucleus from the centre to one side of the cell against the microspore wall.
• Here, the first pollen mitosis takes place that produces a large vegetative cell and a small generative cell containing the haploid nucleus.
• The generative cell that was attached to the microspore wall starts detaching and is engulfed by the vegetative cell forming a unique ‘cell within a cell’ structure.
• The engulfed vegetative cells then undergo pollen mitosis II to form two pollen sperm cells packed in the cytoplasm.

This is the two-stage formation of pollen grains from microsporogenesis and microgametogenesis.

Visit BYJU’S Biology to know more about pollen grains and related topics.

Also check:

• Differentiate between microsporogenesis and megasporogenesis.
• Structure Of Microsporangia
• What are anther and its function in a flower?