Reproduction, Sexual - Research Article from Macmillan Science Library: Plant Sciences

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Sporogenesis and Gametogenesis

Sporogenesis, or spore formation, begins with the differentiation of specialized spore mother cells within the anthers and ovules. The spore mother cells are unique because they undergo meiosis, a division that reduces the chromosome number by one-half, or from diploid to haploid. The haploid spores produced by meiosis in the anthers are called microspores (small spores), while those in the ovules are called megaspores (big spores).

During male gametogenesis, each microspore divides twice to produce a pollen grain, or mature male gametophyte, that consists of only three cells: two sperm cells and one vegetative cell. Female gametogenesis is slightly more complex. Of the four haploid megaspores formed following meiosis of the female spore mother cells, one typically divides four times to produce an eight-nucleate, seven-celled embryo sac, or mature female gametophyte. One of these cells becomes the egg.

Fertilization

Following gametogenesis, the sperm within the...

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This section contains 1,165 words
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Macmillan Science Library: Plant Sciences
Reproduction, Sexual from Macmillan Science Library: Plant Sciences. Copyright © 2001-2006 by Macmillan Reference USA, an imprint of the Gale Group. All rights reserved.
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