Describe the steps involved in cytogenetic harvesting and banding, and explain the purpose of each

What will be an ideal response?

Answer:
 Step 1: Arrest mitotically active cells in metaphase by incubating the sample with colchicine or colcemid that disrupts the spindle apparatus
 Step 2: Incubate the mixture in a hypotonic solution (0.075M KCl) to lyse the erythrocytes and swell the nucleated cells
 Step 3: Fix cells with Carnoy's fixative (3:1 mixture of methanol to glacial acetic acid)
 Step 4: Make a trial slide by adding 3-4 drops of the final cell suspension mixture onto a clean glass slide
 Step 5: Dry the trial slide and examine it by phase microscopy. If the first slide does not show optimal quality, the suspension can be concentrated or diluted to improve the slide's quality.
 Step 6: "Aging" of the slide: Heat the slide in a 60 °C oven overnight to prepare for banding.
 Step 7: Banding: stain chromosomes; Q-banding is done with quinacrine; G-banding is done with Giemsa stain