A trypsin enzyme briefly treats the chromosomes, followed by staining with Giemsa dye. To achieve this arrest, a chemical agent called colchicine or colcemid is introduced to the culture.
Step-by-Step Karyotype Preparation Process Visual Guide
This solution causes the cells to swell, pushing the chromosomes apart from each other, which reduces overlap and improves resolution. This drug disrupts the formation of the mitotic spindle, preventing the cell from dividing and trapping the chromosomes in a state of optimal visibility.
Once collected, these cells are placed in a nutrient-rich growth medium containing phytohemagglutinin (PHA), a substance that stimulates cell division. This culturing period, which typically lasts 72 to 96 hours, is critical because chromosomes are only visible to the naked eye when the cell is actively preparing to divide.
Step-by-Step Visual Guide to the Karyotype Preparation Process
Step Three: Harvesting and Fixing the Cells Once the cells are arrested, they must be harvested and fixed to preserve their structure. This fixative hardens the cells and removes excess moisture, ensuring that the chromosomes remain intact and tightly coiled during the next steps.
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