Individual chromosomes may be tagged with
fluorescent markers. Upon cell fractionation, a stream of cellular material
(including chromosomes) is directed through a narrow capillary in a series
of droplets. If a scanning laser indicates the presence of a chromosome
with an appropriate tag, the droplet containing the chromosome is given
a small electrical charge so that it can be directed into an appropriate
receptacle. Repeated passage of the sample through the cytometer can enrich
the concentration of the chromosome of interest.
