Hi there!

A mature pollen grain (in 2-celled condition) has the following parts:

1. Pollen wall: It has two layers:

(i) Exine - outer ornamented layer made up of sporopollenin (one of the most resistant substance in the living world). It is discontinuous. The regions where sporopollenin is absent are called germ pores. Germ pores are regions from where the pollen tube emerges.

(ii) Intine - inner continuous layer made up of pectin and cellulose. It is flexible and is responsible for the fomation of the pollen tube.

2. Vegetative cell/Tube - A large cell with large cytoplasm containing reserve material and an irregular nucleus. Cytoplasm of this cell extends into the pollen tube.

3. Generative cell - A small spindle-shaped cell floating in the cytoplasm of the vegetative cell. Its nucleus undergoes division to form two male nuclei.

Thanks