Cryofixation of tissues is necessary to be able to study the concentrations of elements by X-ray microanalysis. Simple dissection of heart tissue fragments of the size needed for optimum cryofixation by the conventional methods of plunge or slam freezing leads to the development of ischaemia in the tissue fragments and a consequent redistribution of the diffusible elements. Heart tissue can be frozen in vivo using liquid nitrogen cooled Cu clad pliers, but the morphological detail is preserved better if the cooled pliers are exposed to liquefied propane immediately before freezing, Concentrations of Na are lower and concentrations of K are higher in the tissue which has been frozen in vivo compared to tissue frozen after dissection.
"Cryofixation of Heart Tissue for X-Ray Microanalysis,"
Scanning Microscopy: Vol. 3
, Article 25.
Available at: https://digitalcommons.usu.edu/microscopy/vol3/iss4/25