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Metaphase (from Ancient Greek μετα- beyond, above, transcending and from Ancient Greek φάσις (phásis) 'appearance') is a stage of mitosis in the eukaryotic cell cycle in which chromosomes are at their second-most condensed and coiled stage (they are at their most condensed in anaphase). [1]
This interval includes the G 2 phase and metaphase (annotated as "Meta."). Further information: Karyotype G 2 phase , Gap 2 phase , or Growth 2 phase , is the third subphase of interphase in the cell cycle directly preceding mitosis .
The four main steps of meiosis II are: prophase II, metaphase II, anaphase II, and telophase II. In prophase II, we see the disappearance of the nucleoli and the nuclear envelope again as well as the shortening and thickening of the chromatids. Centrosomes move to the polar regions and arrange spindle fibers for the second meiotic division.
The last check point is located at the site of metaphase, where it checks that the chromosomes are correctly connected to the mitotic spindles. [17] In S phase, the chromosomes are replicated in order for the genetic content to be maintained. [18]
The cumulus-oocyte complex contains layers of tightly packed cumulus cells surrounding the oocyte in the Graafian follicle. The oocyte is arrested in Meiosis II at the stage of metaphase II and is considered a secondary oocyte. Before ovulation, the cumulus complex goes through a structural change known as cumulus expansion. The granulosa cells ...
Micrograph showing condensed chromosomes in blue, kinetochores in pink, and microtubules in green during metaphase of mitosis. In cell biology, the spindle apparatus is the cytoskeletal structure of eukaryotic cells that forms during cell division to separate sister chromatids between daughter cells.
Immediately after meiosis I, the haploid secondary oocyte initiates meiosis II. However, this process is also halted at the metaphase II stage until fertilization, if such should ever occur. If the egg is not fertilized, it is disintegrated and released (menstruation) and the secondary oocyte does not complete meiosis II (and does not become an ...
The second meiotic arrest then occurs after ovulation during metaphase 2 and lasts for a much shorter time than the first arrest. Meiotic arrest occurs mainly due to increased cAMP levels in the oocyte, which regulates key regulator cyclin kinase complex maturation promoting factor (MPF). cGMPs produced by somatic follicular cells further ...