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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.
A microsporangium (pl. microsporangia) is a sporangium that produces microspores that give rise to male gametophytes when they germinate. Microsporangia occur in all vascular plants that have heterosporic life cycles, such as seed plants, spike mosses and the aquatic fern genus Azolla.
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).
The gametophyte is the multicellular structure (plant) that is haploid, containing a single set of chromosomes in each cell. The gametophyte produces male or female gametes (or both), by a process of cell division, called mitosis. In vascular plants with separate gametophytes, female gametophytes are known as mega gametophytes (mega=large, they ...
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.
Microgametogenesis is the process in plant reproduction where a microgametophyte develops in a pollen grain to the three-celled stage of its development. In flowering plants it occurs with a microspore mother cell inside the anther of the plant.