[Histonet] Re: floating petri dish snap freezing question

[Gayle Callis]

Kristen,

I have done it both ways but if you let the tissue float up, it is harder 
to find in the OCT during sectioning.   I often put a very thin OCT layer 
in mold then add tissue to have it located in bottom - then add OCT. After 
than you put mold in canoeing petri dish.  It is sometime hard to push a 
delicate or several pieces into OCT and sort of "glues" them to bottom of 
mold.

Another trick: Put tiny drop of OCT on a dark surface, add biopsies, then 
roll them into a tiny OCT ball, pick up (we like a curved eye forceps for 
this, center tissue/OCT into center/bottom of mold but when you add more 
OCT, go AROUND the little ball of tissues.  The pressure of adding gooey 
OCT around tissues tends to keep everything centered.  You tend to lose 
orientation with this method, something you may not like with gastric bx's.

You can dip tiny tissue in OCT, add to mold so it stays oriented, then add 
OCT slowly and gently. Whatever you do, keep tip of OCT bottle (by laying 
bottle on side) filled to prevent bubbles - the enemy.  tip of bottle can 
be cut off so hole is small and prevent huge flow of goo when dispensing 
OCT. One can always add OCT during freezing - so watch bottom turn white, 
but key word here is is during not after freezing,  you do not want an 
interface of two OCT layers, they will snap part during sectioning at 
times.  Been there, done that, and it was disaster.

We purchase eye forceps for embedding in OCT - these are fine round tips, 
with either straight, half curved or full curved tips.  Sharp points are 
NOT used, to easy to poke holes in tiny tissues.   Arista in New York has 
huge selection and cheap.

Another thing we are using is safety glasses that fit over prescription 
glasses, but the safety glasses have bifocal magnification - wonderful to 
see when handling tiny tissues.  They come in 1, 1.5, 2.5 and 5 
magnification - maybe other,  available from Fisher, Newcomer Supply, and 
MarketLab.

Hopefully this helps, so many ways.

Have a good day

At 06:46 AM 5/11/2005, you wrote:
>Gayle,
>
>I tried out your snap freezing method with the floating petri dish in the
>liquid nitrogen yesterday for some itsy bitsy GI biopsies. I really like it!
>I have a question though. When using this method, do you place your sample
>in the bottom of your mold, then OCT on top, or put a dab (or more) of OCT,
>then the tissue, ... or does it really matter?
>
>Thanks,
>
>Kristen Broomall, HT (ASCP)
>
>
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