Cell division: first embryonic mitosis (Caenorhabditis elegans)
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Description
"Prior to fertilization, C. elegans oocytes are arrested in meiotic prophase with nuclei containing two copies of the diploid genome packaged into recombined bivalent chromosomes. The two rounds of meiotic chromosome segregation that generate the haploid oocyte pronucleus are completed in the zygote after the oocytes are fertilized. During each meiotic division, chromosome segregation is accomplished by a small acentriolar meiotic spindle that forms in the embryo anterior. During anaphase of meiosis I and again in meiosis II, the meiotic spindle associates with the cortex in an end-on fashion, and a highly asymmetric cytokinesis-like event extrudes a polar body (Figure 2; Albertson and Thomson, 1993; Clark-Maguire and Mains, 1994; Yang et al., 2003). In addition to the haploid pronucleus, the sperm brings a pair of centrioles into the oocyte, which lacks centrioles due to their degradation during oogenesis. As meiosis completes, the haploid oocyte and sperm-derived pronuclei, located at opposite ends of the embryo increase in size, becoming visible by DIC microscopy. After entering the oocyte, the sperm-derived centriole pair recruits pericentriolar material and acquires the ability to nucleate microtubules (O'Connell, 2000; Pelletier et al., 2004). Subsequently, the two sperm-derived centrioles separate, forming two centrosomes positioned on either side of the paternal pronucleus. Coincident with chromosome condensation during mitotic prophase, the pronuclei migrate towards each other. After the pronuclei meet, the nuclear-centrosome complex moves to the center of the embryo and rotates to align with the long axis of the embryo (Albertson, 1984; Hyman and White, 1987). The miotitc spindle begins to move towards the embryo posterior during metaphase (Labbe et al., 2004; Oegema et al., 2001), and asymmetric elongation during anaphase contributes to its posterior displacement (Albertson, 1984; Grill et al., 2001). Since the cleavage furrow bisects the mitotic spindle, this displacement results in an asymmetric first cleavage (For more on the mechanisms that generate this asymmetry see Asymmetric cell division and axis formation in the embryo). " From "Cell division" by Karen Oegema, WormBook
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DataNodes
GO:0007052 WBPaper00006305
GO:0009792 WBPaper00004403; WBPaper00025054; WBPaper00006305; WBPaper00013420GO:0051301
GO:0000910GO:0002119 WBPaper00006395;WBPaper00024497 GO:0009792 WBPaper00005654;WBPaper00025054;WBPaper00006395 GO:0035046 WBPaper00006060;WBPaper00025054 GO:0040007 WBPaper00006395;WBPaper00024497 GO:0040010 WBPaper00024497
GO:0040011 WBPaper00006395;WBPaper00005654GO:0002009 WBPaper00029258 GO:0040035 WBPaper00029258 GO:0040018 WBPaper00029258 GO:0007635 WBPaper00001228 GO:0040007 WBPaper00029258 GO:0002119 WBPaper00029258
GO:0009792 WBPaper00025054GO:0040010 WBPaper00005654 GO:0035046 WBPaper00006060 GO:0040022 WBPaper00001883 GO:0010171 WBPaper00005654;WBPaper00029258 GO:0040035 WBPaper00029258 GO:0040007 WBPaper00024497;WBPaper00029258 GO:0002119 WBPaper00005654;WBPaper00024497;WBPaper00029258
GO:0009792 WBPaper00005654;WBPaper00025054;WBPaper00024497;WBPaper00029258GO:0009792 WBPaper00004651;WBPaper00025054;WBPaper00026821
GO:0044254 WBPaper00026631GO:0000003 GO:0002009 GO:0000910 GO:0007109 GO:0009792 GO:0000281 GO:0051301 GO:0040011 GO:0040035 GO:0010171
GO:0040038GO:0000003 GO:0007077 GO:0000910 GO:0009792 GO:0008340 GO:0051301 GO:0040035 GO:0040038 GO:0051726 GO:0002119
GO:0045132GO:0000003 GO:0007077 GO:0000910 GO:0009792 GO:0008340 GO:0051301 GO:0040035 GO:0040038 GO:0051726 GO:0002119
GO:0045132Annotated Interactions
No annotated interactions