Abstract
We recently developed a new autofocusing method
for chromosome aberration scoring which enables
very fast scanning. This system utilizes, near infrared
reflection from the surface of a glass microscope
slide coated with an infrared reflector. In
practice, another coating over the reflecting film is
needed in order to protect the reflecting film from
chemical agents. In the present study, the qualities
of chromosome preparations on slides coated with
SiO2 or SiO over the reflecting film were compared
visually and using the automated system. Chromosome
preparations were made from cultured
human lymphocytes and stained with Giemsa.
Microscopic observation showed that stained
cytoplasmic substances were found around chromosomes
more frequently on SiO2-coated slides than
on SiO-coated slides. Metaphases were found, and
their images were digitized at high magnification by
an automated image analysis system. Cytogeneticists
reviewed the digital images and counted false
positives and metaphases unsuitable for scoring.
“Misframed” metaphases, some of whose chromosomes
were straddling the border of the monitor
field due to errors of automatic centering or zooming,
were observed more frequently on SiO2-coated
slides than on SiO-coated slides. The high rate of
“misframed” metaphases was a major disadvantage
for cytogenetic analysis by automatic facility of
image grabbing. Most “misframed” metaphases
were irregularly spread, suggesting the interference
of SiO2 coating with the circular (uniform) spreading
of metaphases. Preparations on SiO-coated
glass were superior in terms of the clarity of chromosome
images, circular spreading of metaphases,
and suitability for automated image analysis.
