The resulting cells are called gametes, and contain only half the genetic material of the parent cells.These gametes are the cells that are prepared for the sexual reproduction of the organism.Sexual reproduction in eukaryotes is a process whereby organisms form offspring that combine genetic traits from both parents.Chromosomes are passed on from one generation to the next in this process.Multiplicity of gamete types within a species would still be considered a form of sexual reproduction.However, no third gamete is known in multicellular animals.For instance, mate choice and sexual selection can accelerate the evolution of physical differences between the sexes.
In complex organisms, the sex organs are the parts that are involved in the production and exchange of gametes in sexual reproduction.
The gametes produced by an organism are determined by its sex: males produce male gametes (spermatozoa, or sperm, in animals; pollen in plants) while females produce female gametes (ova, or egg cells); individual organisms which produce both male and female gametes are termed hermaphroditic.
Frequently, physical differences are associated with the different sexes of an organism; these sexual dimorphisms can reflect the different reproductive pressures the sexes experience.
Life has evolved from simple stages to more complex ones, and so have the reproduction mechanisms.
Initially the reproduction was a replicating process that consists in producing new individuals that contain the same genetic information as the original or parent individual.