CHROMOSOME ANALYSIS

Chromosome analysis
- karyotyping
  - metaphase chromosomes of a somatic cell are obtained and photographed
    - from this photograph individual chromosomes
      - are cut and arranged according to standard classification
  - for preparation rapidly dividing cells used are
    - lymphocytes from peripheral blood
      - most commonly used
    - fibroblasts from skin
    - bone marrow cells
    - chorionic villi
    - amniotic fluid cells
  - procedure
    - approximately 5 ml of venous blood
      - collected under sterile condition
        
        mixed with heparin to avoid clotting
    - lymphocytes are separated from red cells
      - white cell suspension is then put in culture vial
    - vial contains culture media and fetal calf serum that nourish lymphocytes
      - it also contains phytohemagglutinin that stimulates cell division in lymphocytes
    - culture is then put in an incubator for 3 days
      - the cells divide rapidly
        
        at end of third day colchicin is added
        
        prevents the formation of spindles
        
        thus arrests cell division during metaphase
        
        metaphase chromosome are highly condensed and easily visible
    - cells are separated with centrifuge
      - treated in hypotonic saline
        
        causes to swell and chromosomes to separate

CHROMOSOME BANDING
- G banding
- Q banding
- R banding
- C banding
Fluorescence insitu hybridization
- centromeric probe
- Chromosome specific unique sequence probe
- Whole chromosome paint probe
- Multicolor Spectral Karyotyping