[Histonet] Oddball formalin question!

Greg Dobbin dobbin <@t> upei.ca
Tue Jun 1 11:54:59 CDT 2004

Hello All,
Here is this weeks oddball question! I am tring to make latex casts 
of air sacs in birds (the veterinary people will know that birds have 
air sacs and pneumatic bones that work in conjuction with the lungs 
to facilitate O2 uptake [among other functions such as temp. reg.]).

First of all, we will gently compress the birds body (these birds are 
found dead and brought in by the public-we are not euthanizing!) to 
force out excess air. Then, while suspending the bird by the head 
we will run liquid latex into the trachea. We hope to make casts of 
the communications between the lungs and the various air sacs 
and subcutaneous air pockets. Some these diverticuli are quite 
small so we think we will have to dilute the latex to make it thin 
enough to pass thru these tiny openings. 

So since we are diluting the latex anyway, why not dilute it with 
formalin (10% NBFS) so that we simultaneously begin to fix the 
surrounding structures? However, diluting the latex means that, by 
default, the formalin is also being diluted. My question then is this: 
"What would happen if I made the formalin up partly with latex so 
that the final concentration of formalin in my latex-formalin mixture, 
would be 10% and the latex concentration would still be high 
enough to effectively polymerize?" 

(I have already tried diluting latex with water and it still polymerized 
at a dilution of 1:4 following 18 hours at -20 C [checked after 
thawing of course]). 

I'm thinking the osmotic pressures would be out of whack and the 
formalin probably won't penetrate very far from the latex cast 
anyway, but I thought some you with better knowledge of formalin 
fixation could offer some insight or suggestions before I start 
playing around with this. 

I can't wait see the replies on this one!!

Greg Dobbin
Pathology Lab
Atlantic Veterinary College, U.P.E.I.
550 University Ave.
Charlottetown, P.E.I.
Canada,  C1A 4P3
Phone: (902)566-0744
Fax: (902)566-0851
Making a living is getting; making a life is giving.

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