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Double fertilization or double fertilisation (see spelling differences) is a complex fertilization mechanism of angiosperms. This process involves the fusion of a female gametophyte or megagametophyte , also called the embryonic sac , with two male gametes (sperm).
In flowering plants, double fertilization occurs, which involves two sperm fertilizing the two gametes inside the megagametophyte (the egg cell and the central cell) to produce the embryo and the endosperm.
Most angiosperms reproduce sexually through double fertilization. Different from nucellar embryony, double fertilization occurs via the syngamy of sperm and egg cells, producing a triploid endosperm and a diploid zygotic embryo. In nucellar embryony, embryos are formed asexually from the nucellus tissue.
[22] [23] Once double fertilization is completed, the tube cell and other vegetative cells, if present, are all that remains of the male gametophyte and soon degrade. [23] The female gametophyte of angiosperms develops in the ovule (located inside the female or hermaphrodite flower). Its precursor is a diploid megaspore that undergoes meiosis ...
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The cortical reaction is a process initiated during fertilization that prevents polyspermy, the fusion of multiple sperm with one egg.In contrast to the fast block of polyspermy which immediately but temporarily blocks additional sperm from fertilizing the egg, the cortical reaction gradually establishes a permanent barrier to sperm entry and functions as the main part of the slow block of ...
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However, flowering plants have in addition a phenomenon called 'double fertilization'. In the process of double fertilization, two sperm nuclei from a pollen grain (the microgametophyte), rather than a single sperm, enter the archegonium of the megagametophyte; one fuses with the egg nucleus to form the zygote, the other fuses with two other ...