Sorry, I was off the listserv for a while. I saw your question but I  
don't know if you got an answer. Mouse hair contains pigments which  
reflect light very brightly.


Evelyn Ralston, Ph.D.
Head, Light Imaging Section,
Office of Science & Technology, NIAMS
National Institutes of Health,
Bldg 50, Rm 1535
Bethesda, MD 20892-8023

tel 301-496-6164; FAX 301-402-3417

On Feb 18, 2010, at 11:43 AM, Steffen Dietzel wrote:

> Hello everybody,
>
> when investigating various mouse samples with
> 2-photon excitation, I sometimes see very bright
> "artifact"-signals from what is probably dirt or
> skin pigments. These signals can be actually
> quite annoying, since they are often much
> brighter than fluorochromes and thus can e.g.
> easily trigger the safety shut off of sensitive PMTs.
>
> I assume it is some effect caused by strong
> absorption of these structures. I don't think it
> is fluorescence. It can be caused with very
> different wavelengths, it is present in pretty
> much all channels from blue to far red, and it
> feels too bright for fluorescence. It is also
> different from hair-autofluorescence.  I am
> curious about the nature of this effect. Anybody any ideas?
>
> Steffen
>
> -- 
> ---------------------------------------------------------------------------------------------------
> Steffen Dietzel, PD Dr. rer. nat
> Ludwig-Maximilians-Universität München
> Walter-Brendel-Zentrum für experimentelle Medizin (WBex)
> Marchioninistr. 15, D-81377 München