http://confocal-microscopy-list.275.s1.nabble.com/Tissue-imaging-auto-fluorescence-and-bright-dot-like-signal-tp7588326p7588329.html
That would be my first guess too. Sudan Black or True Black might help
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>Hi Lu,
>
>My guess would be that it could be lipofuscin. I have observed this in
>human brain and mouse brain tissue previously. Also in heart tissue but
>haven't looked at liver. Lipofuscin fluoresces in the green/yellow-red
>emission range with a broad absorption spectrum as well as emission. In
>the human brain tissue, the spots look like fatty droplets and are
>usually adjacent to the nucleus, often in clumps.
>
>Kind regards,
>
>Jacqui
>
>-----Original Message-----
>From: Confocal Microscopy List [mailto:
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>On Behalf Of Yan, Lu
>Sent: Friday, 1 June 2018 3:38 p.m.
>To:
[hidden email]
>Subject: Tissue imaging auto fluorescence and bright dot-like signal
>
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>Dear listers,
>
>I have been imaging mouse brain tissue samples for the last a few days
>using multiple wavelengths laser as illumination (from 405 to 750 nm).
>Initially, the targeted genes in the brain slice were labeled with
>different dyes, e.g. Cy3, Cy5, and Cy7 etc., and I observed quite bright
>dots in corresponding channels, and thought they were RNA molecules.
>However, further examination showed that those dots showed up even in
>'plain tissue' samples (no probes at all), and they virtually showed up
>in almost all fluorescence channels.
>
>The intensity was quite high that we could not distinguish the
>fluorescent probes signals. The plain tissue was snap-frozen and
>sectioned, and fixed with just methanol on coverglasses. I had tried
>different part of brain, different mouse, and they all showed similar
>results, i.e. bright dots cross the tissue sample, sometimes dense,
>sometimes sparse. They also distributed along the z axis, over about 10
>um which is the sample thickness. In some region, I can see larger
>clusters giving much stronger signal. I also tried mouse liver samples,
>and the signal level was very similar to those from brain samples.
>
>I was wondering if anyone had similar experience in imaging tissue
>samples. What could be causing this kind of signal? Any input is welcome
>and appreciated.
>
>Thanks in advance,
>Lu
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