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Polar body twinning is a hypothesized form of twinning in meiosis, where one or more polar bodies do not disintegrate and are fertilized by sperm. [2]Twinning would occur, in principle, if the egg cell and a polar body were both fertilized by separate sperms.
Both polar bodies disintegrate at the end of Meiosis II, leaving only the ootid, which then eventually undergoes maturation into a mature ovum. The function of forming polar bodies is to discard the extra haploid sets of chromosomes that have resulted as a consequence of meiosis.
In female animals, three of the four meiotic products are typically eliminated by extrusion into polar bodies, and only one cell develops to produce an ovum. Because the number of chromosomes is halved during meiosis, gametes can fuse (i.e. fertilization) to form a diploid zygote that contains two copies of each chromosome, one from each parent.
The point of sperm entry defines the dorso-ventral axis - cells opposite the region of sperm entry will eventually form the dorsal portion of the body. [ 1 ] [ 3 ] In the frog Xenopus laevis , the animal pole is heavily pigmented while the vegetal pole remains unpigmented. [ 4 ]
The ovary, surrounding the ovules, develops into the fruit, which protects the seeds and may function to disperse them. [1] The two central cell maternal nuclei (polar nuclei) that contribute to the endosperm, arise by mitosis from the same single meiotic product that gave rise to the egg. The maternal contribution to the genetic constitution ...
The polar vortex is a whirling cone of low pressure over the poles that's strongest in the winter months due to the increased temperature contrast between the polar regions and the mid-latitudes ...
An oocyte (/ ˈ oʊ ə s aɪ t /, oöcyte, or ovocyte is a female gametocyte or germ cell involved in reproduction.In other words, it is an immature ovum, or egg cell.An oocyte is produced in a female fetus in the ovary during female gametogenesis.
Simply put, hibernation is the act of slowing down the metabolic state.During this process, a bear will slow down its heart and breathing rates, and lower its body temperature.