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This creates a 2 or 3 celled male gametophyte which becomes known as the pollen grain once dehiscing occurs. [18] One cell is the tube cell, and the remaining cell/cells are the sperm cells. [19] The development of the three celled male gametophyte prior to dehiscing has evolved multiple times and is present in about a third of angiosperm ...
The male gametophyte gives rise to sperm cells, which are used for fertilization of an egg cell to form a zygote. Megaspores are structures that are part of the alternation of generations in many seedless vascular cryptogams , all gymnosperms and all angiosperms .
An antheridium is a haploid structure or organ producing and containing male gametes (called antherozoids or sperm). The plural form is antheridia, and a structure containing one or more antheridia is called an androecium. [1] The androecium is also the collective term for the stamens of flowering plants.
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 ...
Under favourable conditions, the spore can develop into a new organism using mitotic division, producing a multicellular gametophyte, which eventually goes on to produce gametes. Two gametes fuse to form a zygote, which develops into a new sporophyte. This cycle is known as alternation of generations.
In plants, male reproductive structures include stamens in flowering plants, which produce pollen. [3] Female reproductive structures, such as pistils in flowering plants, produce ovules and receive pollen for fertilization. [4] Mosses, ferns, and some similar plants have gametangia for reproductive organs, which are part of the gametophyte. [5]
The morphology of the microspore consists of an outer double walled structures surrounding the dense cytoplasm and central nucleus. [12] Megaspores contain the female gametophytes in heterosporic plant species. They develop archegonia that produce egg cells that are fertilized by sperm of the male gametophyte originating from the microspore.