What I looked up:
The three broad categories of mammalian stem cells exist: embryonic stem cells, derived from blastocysts, adult stem cells, which are found in adult tissues, and cord blood stem cells, which are found in the umbilical cord. (http://en.wikipedia.org/wiki/Stem_cell)
A gamete is a specialized germ cell that fuses with another gamete during fertilization (conception) in organisms that reproduce sexually. In species which produce two morphologically distinct types of gametes, and in which each individual produces only one type, a female is any individual which produces the larger type of gamete—called an ovum (or egg)—and a male produces the smaller type—called a spermatozoon (or sperm cell) in animals, and a pollen grain in higher plants.
The creation of gametes is gametogenesis, and during it gametocytes divide by meiosis into gametes. Organs that produce gametes are called gonads in animals, and archegonia or antheridia in plants. The term gamete comes from the ancient Greek γαμετης (spouse).
Gametes are haploid cells; that is, they contain one complete set of chromosomes (the actual number varies from species to species). When two gametes fuse (in animals typically involving a sperm and an egg), they form a zygote—a cell that has two complete sets of chromosomes and therefore is diploid. The zygote receives one set of chromosomes from each of the two gametes through the fusion of the two gamete nuclei. (http://en.wikipedia.org/wiki/Gamete)
[edit] Production of male gametes
Researchers at the Whitehead Institute announced in 2003 that they had successfully used embryonic stem cells to produce haploid, male gametes. They found embryonic stem cells that had begun to differentiate into embryonic germ cells and then further differentiated into the male haploid cells. When injected into oocytes, these haploid cells restored the somatic diploid complement of chromosomes and formed blastocysts in vitro.[6] (http://en.wikipedia.org/wiki/Embryonic_stem_cell)
2007-02-02
17:27:12
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raomega8
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