To:  Multiple recipients of list Confocal
 
Recently I have just learned that my name has been mentioned in
a series of messages about slit scanning confocal microscopes.  I thought
that at this time, I thought I might add some observations about these
microscopes.  First, most of my experience is with the Insight instrument by
Meridian.  This microscope was loan to me for a period of two weeks by Craig
Griffin and Noah Hadas.  During this period I used the Insight along with
a Biorad 500 to evaluate changing patterns in the cytoskeleton in Muller cells and photoreceptors.  These observations are subjective; however, they should
prove useful.
 
The real-time confocal microscopes, such as the Insight, are invaluable
for quickly obtaining an understanding of the overall archietecture of
a cell or a tissue.  This advantage seems trivia; however, in the examination
of pathological tissues, a point scanning confocal microscope, such as the
Biorad 500, can be extremely cumbersome.  The necessity of constantly
integrating images and then projecting them to obtain three dimensional
data can be extremely clumsy.  A slit scanning microscope can be extremely
convenient.  It is possible to rapidly scan a tissue and quickly locate
an area of interest.  Once such a region is found, an initial interpetation
of the cell's three dimensional arhitecture can be obtained by quickly
focusing through the tissue plane.  It is amazing how quickly one can
evaluate a comparison between normal and pathological tissues with such a
scope.  In contrast, the Biorad 500--while allowing us to make the same
observations--takes significantly longer to discern the differences between
normal and pathological tissue samples.
 
An additional advantage of the slit scanner is that for visual examination
the eye has an incredible dynamic range.  It is possible to discern detail
in intensely stained regions--an area where a video capture system can have
problems because of "blooming".  In this regard, the Insight microscope has
provided extremely high contrast images of my retinal samples.  It is my
belief that any laboratory that currently operates a laser scanning confocal
microscope (such as the Biorad 500,  600; etc.) would benefit by purchasing
a slit scanner.  The time savings of using a "real time" system is significant
and it makes the use of the point-scanners more efficient.
 
Now as to the Bio-rad slit scanner.  I have used a Bio-rad briefly, and I must
agree with Marty Wessendorf that it produces an extremely nice image.  However,
on the basis of this preliminary observation, I do not wish to give the
impression that its performance is superior or inferior to the Insight.  I have
not had the opportunity to compare both instruments at the same time, nor have
I the opportunity to critically study differences in their performance
characteristics.  I would say at this juncture that the instruments are
comparable in their performance and that they both share the advantages
of providing direct ocular viewing.  Hope this information helps.
 
Brian