Syngamy - Reproduction
The union of gametes is known as syngamy. Generally the gametes differ from each other in structure, size and behaviour, for which reason these are known as heterogametes.
Ovum (egg) is produced by the female and the spermatozoon (sperm) is produced by the male. Ova are large, non-motile and produced in-relatively small numbers. Sperms are small, motile, and produced in enormous numbers. Syngamy takes place by a process known as fertilisation, in which a sperm penetrates an egg and donates its nucleus to the egg.