external fertilization

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• External fertilization — is a form of fertilization in which a zilo cell is united with an egg cell external to the body of the female. Thus, the fertilization is said to occur externally . This is distinct from internal fertilization where the union of the egg and sperm …   Wikipedia

• external fertilization — external fertilization, the fertilization of an egg, especially a human ovum, outside the body, usually by the introduction of sperm into an egg cell surgically removed from an ovary: »The so called test tube babies were of course not monsters… …   Useful english dictionary

• external fertilization — union of the gametes outside the bodies of the originating organisms, as in most fish …   Medical dictionary

• in vitro fertilization — noun : fertilization of an egg in a laboratory dish or test tube ; specifically : fertilization achieved by the mixture usually in a laboratory dish of sperm with eggs that have been surgically removed from an ovary followed by implantation of… …   Useful english dictionary

• cross-fertilization — /kraws ferr tl euh zay sheuhn, kros /, n. 1. Biol. the fertilization of an organism by the fusion of an egg from one individual with a sperm or male gamete from a different individual. 2. Bot. fertilization of the flower of one plant by a gamete… …   Universalium

• Internal fertilization — is a form of animal fertilization of an ovum by spermatozoon within the body of an inseminated animal, whether female or hermaphroditic. This is distinct from external fertilization, where the union of the ova and spermatoza occur outside of the… …   Wikipedia

• reproductive system, animal — Introduction       any of the organ systems by which animals reproduce.       The role of reproduction is to provide for the continued existence of a species; it is the process by which living organisms duplicate themselves. Animals compete with… …   Universalium

• Spawn (biology) — The spawn (eggs) of a clownfish. The black spots are the eyes developing. Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm,… …   Wikipedia

• reproductive behaviour — In animals, any activity directed toward perpetuation of a species. Sexual reproduction, the most common mode, occurs when a female s egg is fertilized by a male s sperm. The resulting unique combination of genes produces genetic variety that… …   Universalium

• Reproductive system — The reproductive system is a system of organs within an organism which work together for the purpose of reproduction. Many non living substances such as fluids, hormones, and pheromones are also important accessories to the reproductive system. [ …   Wikipedia

• Caudata — ▪ amphibian order Introduction also called  Urodela,     one of the major extant orders of the class Amphibia. It includes salamanders (salamander) and newts (newt). The relatively small and inconspicuous salamanders are important members of… …   Universalium