The second stage is metaphase I. Here the paired up homologous chromosomes line up at the equator and the spindle fibbers attach to the chromosomes in a way that ensures that for each homologous pair, one chromosome moved to one pole and the other moves to the opposite pole. The third st...
About 2 per cent of chiasmata, considerably more than in previous studies, occur in nonproximal chromosome regions in this material, while 12.9 per cent of metaphase I cells contained one or more multivalents, again exceeding most previous estimates. Meiotic regularity in this material was also ...
metaphase中期、Anaphase后期、Telophase末期）5.2、mitosis有丝分裂1).interphase分裂间期：•G1:合成前期，细胞生长，各种生物大分子如mRNA、蛋白质合成，基因表达，决定细胞是否分化。•Sphase：(synthesis合成期)DNAissynthesized，DNA复制，染色体复制。•G2：合成后期，积蓄能量，以备分裂。2).mitoticstage分裂期...
Meiosis 2 Prophase 2 In this stage, the nuclear membrane as well as the nuclei break and the spindle fibers reappear. The chromosomes then start migrating to the equator of the cell. Metaphase 2Chromosomes line up at the second metaphase plate at the center of the cell. The kinetochores ...
Release of the metaphase block was obtained by fertilization or treatment with ionophore A 23187 or excess KCl. Ionophore application is effective in the absence of calcium. These treatments are ineffective when applied to GV prophase-blocked oocytes. In contrast, such oocytes resumed maturation up ...
In order to verify the theory of non-homologous pairing in the male meiotic metaphase of Drosophila melanogaster, particular crosses were carried out with In(1)sc 4 sc 8 males, with or without the inversion In(2)SM 5, Cy on the second chromosome. The results seem to indicate the existence...
Mammalian eggs remain arrested at metaphase of the second meiotic division (metII) for an indeterminate time before fertilization. During this period, which can last several hours, the continued attachment of sister chromatids is thought to be achieved by inhibition of the protease separase. ...
From the study of metaphase II it appears that the extra chromosomes segregate in half of the spermatocytes II. Some abnormal spermatocytes, resulting from nondisjunction of chromosomes at mitosis or at first division of meiosis, or from precocious division of chromosomes at first division of meiosis...
Recent studies found that mouse oocytes with damaged DNA can resume meiosis and undergo germinal vesicle breakdown (GVBD), but then arrest in metaphase of meiosis I in a process involving spindle assembly checkpoint (SAC) signaling. Such a mechanism could help prevent the generation of metaphase ...
Emi2Phosphate-binding PocketXErp1To ensure the correct euploid state of embryos, it is essential that vertebrate oocytes await fertilization arrested at metaphase of meiosis II. This MII arrest is mediated by XErp1/Emi2, which inhibits the ubiquitin ligase APC/C (anaphas...