Fertilization

Definition

The fusion of a male and female gamete to form a diploid zygote, initiating development of a new organism. In arthropods, fertilization may occur internally (within the female reproductive tract, as in most insects and arachnids) or externally (eggs released and fertilized outside the body, as in many aquatic crustaceans). The process restores the diploid chromosome number and activates embryonic development.

Etymology

From Latin fertilis, meaning 'fruitful' or 'productive'.

Example

In honey bees (Apis mellifera), fertilization occurs in the oviduct when sperm stored in the spermatheca are released to meet an ovum; unfertilized eggs develop into haploid males (drones) via arrhenotoky, while fertilized eggs become diploid females.

Synonyms

• syngamy

Related Terms

• insemination
• oviposition
• Parthenogenesis
• Arrhenotoky
• spermatheca
• zygote
• Gamete

Usage Notes

Specialists distinguish fertilization (gamete fusion) from insemination (sperm transfer) and pollination (gamete transfer in plants). In arthropod literature, 'fertilization' sometimes loosely includes insemination, but precise usage reserves it for the cellular fusion event. Some insects (aphids, certain ants, wasps) routinely reproduce by parthenogenesis, bypassing fertilization entirely.