Viljastuda

Viljastuda is an Estonian verb meaning to become fertilized or to be fertilized. The corresponding active form viljastada refers to the act of fertilizing. In scientific contexts, viljastumine is the process of fertilization itself, and it can apply to both plants and animals. The concept describes the fusion of male and female genetic material that creates a new, genetically distinct organism or a seed.

In plants, fertilization involves pollen from the male anther reaching the female ovule. Pollen germinates on the stigma and a pollen tube delivers sperm cells to the ovule. In flowering plants (angiosperms) a process called double fertilization occurs: one sperm fuses with the egg to form a zygote, and another fuses with a central cell to form endosperm, which nourishes the developing embryo. Gymnosperms have fertilization that ultimately produces a fertilized egg and seed, though the details differ from angiosperms.

In animals, fertilization is the union of a sperm cell with an egg cell, resulting in a zygote that begins embryonic development. Modes of fertilization vary from external (eggs and sperm released into the environment) to internal (sperm fertilizing the egg inside the body). Fertilization combines genetic material from two parents and is a central event in sexual reproduction, contributing to genetic variation and the initiation of development.

Overall, viljastuda describes a fundamental reproductive event that underpins heredity, development, and biodiversity. See also fertilization, pollination, and zygote.