karyotyping is done at which phase of cell cycle?

Discussion in 'Question Zone' started by guest2011, Aug 22, 2012.

  1. guest2011

    guest2011 Moderator


    Karyotypes are prepared from mitotic cells that have been arrested in the metaphase or
    prometaphase portion of the cell cycle, when chromosomes assume their most condensed
    conformations . A variety of tissue types can be used as a source of these cells. For cancer
    diagnoses, typical specimens include tumor biopsies or bone marrow samples. For other
    diagnoses, karyotypes are often generated from peripheral blood specimens or a skin biopsy. For
    prenatal diagnosis , amniotic fluid or chorionic villus specimens are used as the source of cells.
    The process of generating a karyotype begins with the short-term culture of cells derived from a
    specimen. After a period of cell growth and multiplication, dividing cells are arrested in metaphase
    by addition of colchicine, which poisons the mitotic spindle. The cells are next treated with a
    hypotonic solution that causes their nuclei to swell and the cells to burst. The nuclei are then
    treated with a chemical fixative, dropped on a glass slide, and treated with various stains that
    reveal structural features of the chromosomes.

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