What is Fertilization?

Fertilization is the process by which the male and female reproductive cells, or gametes, unite to form a new individual organism. In animals, fertilization typically occurs inside the female’s body and involves the union of an egg cell (ovum) with a sperm cell. The resultant fertilized egg, known as a zygote, carries both parents’ genetic material and has the capacity to grow into a new person.

In humans and most animals, fertilization is a necessary step in the process of sexual reproduction. However, some plants and some types of algae and fungi can reproduce asexually without the need for fertilization.

Fertilization is a complex process that involves several steps, including the release of eggs and sperm from the reproductive organs, the movement of the gametes towards each other, and the fusion of the gametes to form the zygote. In animals, fertilization is usually triggered by the presence of a specific chemical signal, called a pheromone, that is produced by the opposite sex.

The fusing of the two gametes’ membranes, which results in the creation of a channel that allows the material to go from one cell to the other, is the first critical event in fertilization. In developed plants, pollination occurs before fertilization, when pollen is delivered to and makes contact with the female gamete or macrospore. In advanced species, fusion is typically followed by a single spermatozoon penetrating the egg. A cell (zygote) created after conception is capable of cell division to create a new person.

Egg activation, which enables cell division in the egg, is the main outcome of fertilization. However, in parthenogenesis, where fertilization does not take place, activation of an egg may be performed through the intervention of physical and chemical factors rather than necessarily requiring the involvement of a spermatozoon. Parthenogenesis is the typical method of reproduction for invertebrates like aphids, bees, and rotifers.