Avoiding shrinkage Re: [Histonet] Embedding human cartilage/joint tissue in plastic

[Gayle Callis]

A clever, simple use of low voltage xray machines i.e FAXITRON can help you 
out.

We did specimen radiographs with a FAXITRON, and underexposed the sample to 
enhance soft tissues i.e tumors and cartilage.  These will be like 
"contact" photographs, showing no shrinkage of the soft tissue 
components.  After fixation DO not decalcify, radiograph the sample then 
decalcify (by the way, xray is the most sensitive decalcification endpoint 
determination) and do another radiograph at the same initial exposure.  You 
can do thicker slabs even 5 mm thick but make sure you are consistent with 
thickness of slab, a good bone saw will do this - Buehler Isomet or the 
MarMed saw, a lovely device.

The bones can be NBF fixed but you avoid all dehydration/clearing and heat 
of paraffin which will cause shrinkage. If you have to know exact edge of 
cartilage, a radioopaque substance can be painted on surface of cartilage 
to define that sharp edge.

  There is a publication where a group tested the amount of shrinkage you 
get with both paraffin and plastic processing, results were interesting in 
that BOTH methods caused as much as 20% shrinkage, possibly more of the 
hard tissue, so you will not avoid shrinkage with plastic embedding methods 
involving alcohols or any other solvent to remove water.

  Since cartilage has a high water content and by doing specimen 
radiography, you can avoid alcohols, clearing agents and heat of paraffin 
that cause shrinkage by water removal.


At 01:22 PM 8/1/2005, you wrote:
>
>
>We are trying to use histology to validate our method of measuring 
>cartilage thickness on wrist bones using ?CT scans. Initially we tried 
>fixing a trapezoid fragment in formalin, de-mineralizing it, and embedding 
>it in paraffin before slicing it into 5 ?m sections. This method led to 
>non-uniform shrinkage of the tissue and clearly visible artifact. We would 
>like to try a method, perhaps embedment in plastic, which will yield a 
>more accurate measure of cartilage thickness. Does anyone have any 
>suggestions?
>
>Thank you for your suggestions.
>
>
>Jane Casey
>Department of Orthopaedics
>Brown Medical School / Rhode Island Hospital
>Providence, RI 02912
>Jane_Casey <@t> Brown.edu <mailto:Jane_Casey <@t> Brown.edu>
>
>_______________________________________________
>Histonet mailing list
>Histonet <@t> lists.utsouthwestern.edu
>http://lists.utsouthwestern.edu/mailman/listinfo/histonet

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 (lab with voice mail)
406 994-4303 (FAX)