ageing rings in sharks

<< Previous Message | Next Message >>
From:"Marshall, Sharon," <>
Content-Type:text/plain; charset=US-ASCII

Hi histonetters,
I have a student in my lab. who wants to view ageing rings in cat 
shark vertebrae.  This has been done before (previous papers) using 
resin sections and tetracycline fluorescence.  These sections are a 
couple of mm thick and viewed under ultra violet light. She seems to 
think it might be possible to process to wax, cut 7 micron thick 
sections and still see these rings.  We tried some samples she had 
which are 10 years old and have been in 70% alcohol all that time.(no 
tetracycline present in sharks in these samples)
We decalcified in 5% formic acid, processed to wax and then stained 7 
micron sections with H&E, Tol. Blue. No rings.  I think these rings 
are only possible to view using thicker sections thick or the 
specimens are to old.   I know that to see tetracycline flourescence 
one needs to alcohol fix and resin embed hence the processing in the 
previous papers. 
Finally, we are going to try fresh samples but I am wondering if we 
are not wasting our time.  I need to convince her that resin and 
thicker sections cut with a diamond saw is the
way to go even if no tetracycline is present in the samples.
Any opinions,help would be great.
Sharon Marshall
Anatomy & Cell Biology
University of Cape Town
South Africa

<< Previous Message | Next Message >>