SPECIMEN PREPARATION FOR QUANTITATIVE MICRORADIOGRAPHY

The great importance of the pretreatment of biological objects for quantitative microradiography is discussed. Freeze-drying was proved a suitable method in obtaining dehydrated sections without any measurable change in the dry substance. The different steps of the freeze-drying procedure are analyzed with special reference to their effects on mass determinations. The most important errors are the effects of shrinkage and incomplete drying, their magnitude being discussed. For microradiographic determination of dry mass per unit volume the thickness of the freeze-dried tissue sections must be measured. Different methods for thickness determination are discussed and for freeze-dried sections a procedure for focusing in a microscope proved appropriate, the error in a single determination being less than 1 μm. © 1969 Springer-Verlag.