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fertilization |
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fertilization, in biology, process in the reproduction reproduction, capacity of all living systems to give rise to new systems similar to themselves. The term reproduction may refer to this power of self-duplication of a single cell or a multicellular animal or plant organism. ..... Click the link for more information. of both plants and animals, involving the union of two unlike sex cells (gametes), the sperm sperm or spermatozoon (spûr'mətəzō`ən, –zō`ŏn) ..... Click the link for more information. and the ovum ovum (ō`vəm), in biology, specialized plant or animal sex cell, also called the egg, or egg cell. ..... Click the link for more information. , followed by the joining of their nuclei. In the flowers of higher plants, the process occurs after pollination pollination, transfer of pollen from the male reproductive organ (stamen or staminate cone) to the female reproductive organ (pistil or pistillate cone) of the same or of another flower or cone. ..... Click the link for more information. has enabled the sperm to contact the egg cell in the plant's ovary. In lower plants and in animals the sperm is actively motile and swims to the egg through an external aqueous medium or through a fluid environment within the reproductive tract of the female. The fundamental principle of fertilization is the same in all organisms. The first sperm to establish successful contact is absorbed by the ovum and the two nuclei unite, thus combining the hereditary material of both parents (see genetics genome, or characteristic set of genes, that contains the total genetic information for an individual organism. In many familiar organisms two genes for each trait are present in each individual, and these paired genes, both governing the same trait, are called alleles. ..... Click the link for more information. ). In higher forms, the sperm contact initiates cell division in the fertilized egg (zygote), and the subsequent embryo embryo (ĕm`brēō), name for the developing young of an animal or plant. ..... Click the link for more information. develops into a new individual. Cross-fertilization indicates fusion of a sperm of one hermaphroditic plant or animal with an ovum of another, as distinguished from self-fertilization, in which ovum and sperm of the same individual are fused. fertilizationReproductive process in which a male sex cell (sperm) unites with a female sex cell (egg). During the process, the chromosomes of the egg and sperm will merge to form a zygote, which will divide to form an embryo. In humans, sperm travel from the vagina through the uterus to a fallopian tube, where they surround an egg released from an ovary usually two or three days earlier. Once one sperm has fused with the egg cell membrane, the outer layer becomes impenetrable to other sperm. See also cross-fertilization, self-fertilization. |
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Ferry, Jules Ferry, Orris Sanford Ferrying Fersen, Count Fredrik Axel Fersen, Count Hans Axel fertile Fertile Crescent fertilisation Fertility fertility drug fertility rites fertilization fertilizer Ferto tó Fès |
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