At this point the cells are ready for analysis.

Suitable metaphases are located under the microscope
with about 100x magnification and
are subsequently examined at about 1250x
magnification. During direct analysis with the
microscope, the number of chromosomes and
the presence or absence of all chromosomes
and recognizable chromosome segments are
noted. Since the preparation procedure itself
may induce deviations from the normal chromosome
number or structure in some cells,
more than one cell must be analyzed. Depending
on the purpose of the analysis, between 5
and 100 metaphases (usually 10–15) are examined.
Some of the metaphases are photographed
with the microscope and can subsequently
be cut out of the photograph (karyotyping).
In thisway a karyotype can be obtained
from the photograph of a metaphase. The time
needed for a chromosome analysis varies depending
on the problem, but is usually 3–4
hours. Analysis and karyotyping time can be
shortened by computer procedures.