Understanding the Generative Cell in Pollen Grains

A pollen grain represents the male gametophyte in seed plants. Before or during the germination process, the generative cell within the pollen grain undergoes division. A typical mature pollen grain, at the time of shedding, is often a two-celled structure consisting of a larger vegetative cell (or tube cell) and a smaller generative cell.

The vegetative cell is responsible for forming the pollen tube, which grows down towards the ovule. The generative cell's role is to produce the male gametes necessary for fertilization.

Division of the Generative Cell

When the pollen grain lands on a compatible stigma and germinates, the generative cell undergoes mitotic division. This division can occur either:

• Before the pollen grain is shed (in about 40% of angiosperms), resulting in a 3-celled pollen grain at shedding (one vegetative cell and two male gametes).
• After the pollen grain is shed, while it is growing in the pollen tube (in the remaining 60% of angiosperms).

In either case, the result of the generative cell's division is the formation of two male gametes. These two male gametes are crucial for the process of double fertilization in angiosperms, where one male gamete fuses with the egg cell to form the zygote, and the other male gamete fuses with the polar nuclei to form the primary endosperm nucleus.

Therefore, the generative cell of the pollen grain divides to form two male gametes.