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Pollen tube elongation is an integral stage in the plant life cycle. The pollen tube acts as a conduit to transport the male gamete cells from the pollen grain—either from the stigma (in flowering plants) to the ovules at the base of the pistil or directly through ovule tissue in some gymnosperms.
Microgametogenesis is the process of the formation of the male gametophyte. During pollination, the female gametophyte communicates with the pollen tube to ensure that it comes in contact with the ovule. [6] When contact is made, the pollen tube grows through the micropyle opening into a synergid cell, that dies when this occurs.
As the male gametophyte matures, the generative cell passes into the tube cell, and the generative cell undergoes mitosis, producing two sperm cells. Once the pollen grain has matured, the anthers break open, releasing the pollen. The pollen is carried to the pistil of another flower, by wind or animal pollinators, and deposited on the stigma ...
Gametogenesis is a biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes.Depending on the biological life cycle of the organism, gametogenesis occurs by meiotic division of diploid gametocytes into various gametes, or by mitosis.
The pollen enters a pollen chamber close to the nucellus, and there it may wait for a year before it germinates and forms a pollen tube that grows through the wall of the megasporangium (=nucellus) where fertilisation takes place. During this time, the megaspore mother cell divides by meiosis to form four haploid cells, three of which degenerate.
The whole pollen grain is moved (e.g. by an insect or by the wind) to an ovule (megagametophyte), where a sperm is produced which moves down a pollen tube to reach the egg. A female zygote develops by mitosis into a megasporophyte, which at maturity produces one or more megasporangia.
Megasporogenesis, formation of the megaspores in the megasporangium (nucellus) by meiosis; Megagametogenesis; development of the megaspore(s) into the megagametophyte(s) which contains the gametes. [2] In gymnosperms and most flowering plants, only one of the four megaspores is functional at maturity, and the other three soon degenerate.
Allogamy is the fertilization of flowers through cross-pollination, this occurs when a flower's ovum is fertilized by spermatozoa from the pollen of a different plant's flower. [15] [16] Pollen may be transferred through pollen vectors or abiotic carriers such as wind. Fertilization begins when the pollen is brought to a female gamete through ...