Zygote or Egg is the diploid cell resulting from the union of the nuclei of two mutually compatible cells. It's the product of sexual reproduction.
In animals, the zygote is called egg and results from the union of two gametes, it is a cell capable of storing the genetic characteristics of the parents, being able to generate all the cell lines of the organism adult.
Zygote is the cell formed by the fusion of male and female gametes, and which will give rise, through differentiation and embryogenesis, to the new being of the species, primarily in the form of an embryo. In the specific case of humans, a zygote has 23 pairs of chromosomes, that is, 46.
In plants, the zygote will give rise to the sporophyte, the stage that produces spores; the germination of these spores gives rise to the gametophyte, capable of producing haploid gametes.
In spermatophytes, the zygote first develops into an embryo that lies within the seed, while in pteridophytes, the zygote develops directly into the adult plant.
In fungi, a zygote is the cell resulting from the fusion of the nuclei of two sexually compatible hyphae and gives rise to a zygospore, which produces a new hypha whose nuclei will go over meiosis and generate spores capable of developing into new individuals haploids.
See also the meaning of Fertilization and Fetal develop and meet the Types of Reproduction: asexual and sexual.
