fertilisatsioon
Fertilisatsioon, or fertilization, is the biological process by which a male gamete (sperm) fuses with a female gamete (egg) to form a zygote, initiating development in sexually reproducing organisms. It restores the diploid chromosome number and activates embryogenesis. Fertilization can occur internally, within the female’s body, or externally in the environment.
In animals, fertilization typically involves recognition of compatible gametes, sperm penetration of protective layers around the
In plants, fertilization occurs after pollen reaches the stigma and germinates a pollen tube that grows toward
Natural fertilization can be external (e.g., many fish and amphibians) or internal (mammals, birds, many reptiles).