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In the brown alga Fucus, all four egg cells survive oogenesis, which is an exception to the rule that generally only one product of female meiosis survives to maturity. In plants, oogenesis occurs inside the female gametophyte via mitosis. In many plants such as bryophytes, ferns, and gymnosperms, egg cells are formed in archegonia.
The repair process used likely involves homologous recombinational repair. [26] [27] [28] Prophase arrested oocytes have a high capability for efficient repair of DNA damages. [27] In particular, DNA double-strand breaks can be repaired during the period of prophase arrest by homologous recombinational repair and by non-homologous end joining. [29]
This is an accepted version of this page This is the latest accepted revision, reviewed on 22 November 2024. Process in which chromosomes are replicated and separated into two new identical nuclei For the type of cell division in sexually reproducing organisms used to produce gametes, see Meiosis. For excessive constriction of the pupils, see Miosis. For the parasitic infestation, see Myiasis ...
The eukaryotic cell cycle consists of four distinct phases: G 1 phase, S phase (synthesis), G 2 phase (collectively known as interphase) and M phase (mitosis and cytokinesis). M phase is itself composed of two tightly coupled processes: mitosis, in which the cell's nucleus divides, and cytokinesis, in which the cell's cytoplasm and cell membrane divides forming two daughter cells.
Asymmetric division is a process of mitosis in which one oogonium divides unequally to produce one daughter cell that will eventually become an oocyte through the process of oogenesis, and one daughter cell that is an identical oogonium to the parent cell. This occurs during the 15th week to the 7th month of embryonic development. [2]
During oogenesis, the oogonia become primary oocytes. Oocytes (immature ova) residing in the primordial follicle of the ovary are in a non-growing prophase arrested state, but have the capacity to undergo highly efficient homologous recombinational repair of DNA damages including double-strand breaks. [ 1 ]
An immature ovum is a cell that goes through the process of oogenesis to become an ovum. It can be an oogonium , an oocyte , or an ootid . An oocyte, in turn, can be either primary or secondary, depending on how far it has come in its process of meiosis .
As the DTC undergoes mitosis, the cells move proximally along the organism and passing from the mitotic-proliferative region into the meiotic cycle. During this cycle, the cells complete meiotic prophase before passing into the zone of oogenesis (or spermatogenesis, depending on the sex and age of the organism). [2] [4] [5]