[Histonet] detached retinas

[Tyrone Genade]

Hello,

I'm having a problem with detached retinas.

I fix my fish, whole, in 4% PFA for 24 hours. The belly is slit to allow
better penetration of the PFA. The entire fish is about 4 cm long and about
6 mm wide. From the 4% PFA I proceed to decalsify the fish in 14% EDTA (pH
7.6). This goes on for 3 days. From there the tissues is passaged through
70% to 95% to 100% ethanol and then cleared in methylbenzoate before being
wax impregnated.

My current hypothesis is that the thick eye membrane is impeding the
penetration of the PFA. As consequence, when I passage into the EDTA and
alcohol I get rapid dehydration of the tissue and the change in pressure in
the eye causes the detached retinas. How feasible is this hypothesis and
what others can you come up with?

I am currently testing this hypothesis. I have fixed 2 fish in PFA but I
have punctured the eyes of one of the fish to improve PFA penetration.

The sections I have cut of the first specimen show no issues with soft
tissue fixation. My only problem is that the retina has detached formed
several waves of tissue in the eye. The sections look good except for the
eye issues. I never had this issue with Bouin's.

Thanks

-- 
Tyrone Genade

P.S. Incidentally, I am now using Paraplast Plus cat number 19216 (
http://www.emsdiasum.com/microscopy/products/histology/embedding.aspx ) and
it is a dream to work with compared to what I was using. It is soft and
cuts beautifully, the ribbons look good and impregnation is great (even by
manual processing).

Orange City, Iowa
tel: (+1) 712 230 4101
http://tgenade.freeshell.org
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