A pollen grain is a microscopic body that contains the male reproductive cell of a plant. It is crucial in a plant’s fertilization process. Some are tiny orbs, while others are egg-shaped. This tough shell lie two cells: the tube cell, which will eventually become the pollen tube, and a generative cell, which contains the male sperm nuclei needed for fertilization. here are three main components of a pollen grain. The inside of the grain is made up of cytoplasm. This fluid medium houses the aforementioned living cells, keeping them moist and alive. The outer shell is made up of two layers. The inside layer has aptly named the intine (think interior). It is composed partly of cellulose, a common component in the cell walls of plant cells. The tough-as-nails outer layer is known as the exine.