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The development of the three celled male gametophyte prior to dehiscing has evolved multiple times and is present in about a third of angiosperm species allowing for faster fertilization after pollination. [20] Once pollination occurs, the tube cell grows in size and if the male gametophyte is only 2 cells at this stage, the single sperm cell ...
In heterosporous seedless vascular plants, modified leaves called microsporophylls bear microsporangia containing many microsporocytes that undergo meiosis, each producing four microspores. Each microspore may develop into a male gametophyte consisting of a somewhat spherical antheridium within the microspore wall.
However, the parent sporophyte may be monoecious, producing both male and female gametophytes or dioecious, producing gametophytes of one gender only. Seed plant gametophytes are extremely reduced in size; the archegonium consists only of a small number of cells, and the entire male gametophyte may be represented by only two cells. [27]
There are two key differences between mammalian and plant gametogenesis. First, there is no predetermined germline in plants. Male or female gametophyte-producing cells diverge from the reproductive meristem, a totipotent clump of developing cells in the adult plant that creates all the flower's features (both sexual and asexual structures).
In the most common type of megagametophyte development in flowering plants (the Polygonum type), three mitotic divisions are involved in producing the gametophyte, which has seven cells, one of which (the central cell) has two nuclei that later merge to make a diploid nucleus.
Megagametogenesis creates the female gametophyte, which is an integral part of pollination, a very prominent process in plants. The male counterpart to megagametogenesis is called microgametogenesis. Microgametogenesis is the process of the formation of the male gametophyte.
The parts of a flower Double fertilization. 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).
Various plant groups have differing methods by which the gametes produced by the male and female gametophytes come together and are fertilised. In bryophytes and pteridophytic land plants, fertilisation of the sperm and egg takes place within the archegonium. In seed plants, the male gametophyte is formed within a pollen grain.