Intestine Re: [Histonet] positioning tissues in OCT

[Gayle Callis]

For intestine, we rinse the lumen with PBS to remove fecal matter (it will 
be very crunchy when cryosectioned), then fill the lumen with pure OCT 
using a large gauge syringe needle, dulled.  This distends the lumen a bit 
for support of inner structure (no bubbles, no flattened villi), OCT will 
ooze out a bit but in general does the job.  You can either freeze longer 
gut segments then cut into workable sizes for double embedding or OR cut 
the OCT filled gut into shorter segements for embedding in Tissue Tek 
cryomold.  Jackie O' Connor's suggestion was right on for double embedding, 
orientation on end, etc.

Generally we mount block on metal disk then build up OCT around the 
block.  Flat embedding/freezing/reorietation is our method for spinal cord 
too.

Beware of which cryoembedding media you use to fill lumen -  try different 
ones.  We tried one media that was tested on human tissues only and 
injecting it into a lumen of mouse intestine failed to give good sections - 
the media didn't coat villi properly, and these were squished up and 
laddered.

At 12:25 PM 12/1/2006, you wrote:
>For our paraffin blocks we embed rat gi on end so when sectioned you get
>a little circle of tissue. Any suggestions on how to do this for
>cryosections?  The fresh tissues have been too soft and flexible to stay
>standing up in the OCT until it freezes. Thanks.
>
>
>
>Renee' Till, HT
>
>Research Assistant
>
>Arkansas Children's Nutrition Center
>
>1212 Marshall St./N2021
>
>Little Rock, AR 72202
>
>Office (501)364-2785
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>Fax (501)364-3161
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Gayle Callis
MT,HT,HTL(ASCP)
Research Histopathology Supervisor
Veterinary Molecular Biology
Montana State University - Bozeman
PO Box 173610
Bozeman MT 59717-3610
406 994-6367
406 994-4303 (FAX)