En bloc decalcification of vertebrae + spinal cord

From:Alex Knisely (by way of Histonet)

When in fellowship and early in post-graduate work I conducted en bloc
autopsy dissections of posterior fossa and cervical spine, with spinal cord
in situ, in several infants and foetuses with generalised bone disorders.
Views of some of the results are published in Knisely AS, Singer DB.  A
technique for necropsy evaluation of stenosis of the foramen magnum and
rostral spinal canal in osteochondrodysplasia.  Hum Pathol 1988; 19:1372-5.

Of course mineralisation was less advanced in those tissues than will be
the case in adults.

The specimens themselves were rarely more than 8 inches in greatest
dimension and could be accommodated in gallon jars with dilute formic acid
and a "chelating / decalcifying resin".  After two weeks in formalin (I
wanted to ensure that the high-lipid neural tissues were adequately fixed)
the specimens were transferred to the decalcifying set-up and I checked
them daily to see if the most densely mineralised portions, the petrous
bones of the skull base, could be penetrated easily by a straight pin.
When those bones could be so penetrated I experienced no difficulty at all
in taking and trimming sections of vertebral column with spinal cord in
situ.  The blocks could be accommodated within standard cassettes (although
some bits of spinous processes had to be sacrificed!) and histologic detail
was very good indeed; damage to the neuraxis could be demonstrated using
standard stains such as Luxol fast blue.

You will have your greatest difficulty in ensuring, for purposes of an
atlas, that the standard conformational curve of the spinal column is
retained during fixation and processing.  Please discuss carefully with
your investigators how this is to be achieved (suspension in a large, long
graduated cylinder?) and whether your transverse / coronal incisions
through the vertebral column are to be made perpendicular to the long axis
of the spinal cord / vertebral unit 1) at the inclination of that long axis
from the vertical or 2) to the vertical long axis.

Good luck!

Alex K

At 10:31 07/03/02 -0800, A. Erickson wrote:
>Good morning,
>I have been asked to prepare sections of vertebrae with spinal cord still
>in position, ultimately for an atlas.  Major concerns are decalcification
>without destroying the cord, maintaining the proper relationship of cord
>elements and bone elements, and processing with minimal shrinkage.  Any
>information which might help with this project (ideas, suggestions,
>warnings, protocols...) is greatly appreciated.  Andra Erickson, Research
>Technologist, University of Washington RPRC, Neuro Division.
Alex Knisely, MD
Consultant Histopathologist


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