Bone and other ossified tissue must have calcium removed for the tissue to be soft enough to section. This is achieved by placing the tissue in a decalcification solution based around an acid. Over-decalcification of tissue prior to processing can result in a number of artifacts in the final sections.
Factors associated with over-decalcification:
(1) strong acid in the decalcification solution
(2) time in decalcification solution too long
(3) poor fixation of the tissue
Artifacts associated with excessive decalcification:
(1) loss of nuclear detail, eventually with complete loss of nuclear staining
(2) decrease in basophilic staining
In the worst cases the histologic sections cannot be interpreted.
Ways to avoid:
(1) Use the weakest acid possible.
(2) Use the shortest decalcification period possible.
(3) Cut pieces of bone small and/or thin so that there is rapid penetration.
(4) Ensure that the tissue is well fixed.
(5) Monitor the tissue during decalcification, which may include taking X-rays.
