====== 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