Effect of delay in cryofixation on the elemental composition of biopsies and post mortem specimens of the thyroid gland.

The time between the excision and cryofixation of a biopsy is most important regarding its elemental composition as demonstrated by an investigation of the thyroid glands of rats and pigs. Biopsies taken and cryofixed immediately served as control specimens. Biopsies that were allowed to stand at room temperature for 20 min before cryofixation and specimens cryofixed at 1 h post mortem were also investigated. Significant changes in the ion concentration of the cells and colloid were apparent in biopsies in which cryofixation was delayed for 20 min and in thyroids cryofixed 1 h post mortem. It was demonstrated that redistribution of electrolytes occurs within 1h post mortem and that similar changes occur in biopsies allowed to stand for 20 min at room temperature before cryofixation. The results stress the importance of immediate cryofixation after surgical excision of a biopsy. This is especially important since numerous elemental changes due to delayed cryofixation resemble those which occur in pathological processes.