THE PRESERVATION OF CYTOLOGICAL 



AND HISTOCHEMICAL DETAIL 



BY CONTROLLED TEMPERATURE FREEZE-DRYING 



»G. J. CUNNINGHAM, LUCILLE BITENSKY, J. CHAYEN 



and A. A. SILCOX 



Department of Pathology, Royal Collège of Surgeons, 

 Lincoln's Inn Fields, London. 



The basis of ail histochemistry is the perfect préservation of ail com- 

 ponents of the tissue. The technique by which cells are frozen, dried 

 and then sectioned has certain drawbacks, which will be discussed. 

 A method will be described by which tissue is frozen relatively slowly 

 to — 70°C and sectioned at —20 to — 25°C. The cytological préservation 

 is such that half an hour after injecting a liver carcinogen its effect 

 on the structure of liver mitochondria can be observed. The distribution 

 of enzymes such as allcaline phosphatase or dehydrogenases and enzy- 

 matic metabolism of a carcinogenic agent hâve been studied without 

 prior fixation, the sections being treated very much as are the tissue 

 slices used by biochemists. The localization of lipids is demonstrable 

 readily; in particular délicate lipid-protein bonds are unaffected by 

 this preparatory procédure. Molecular orientation too is well preserved. 

 This is shown best in plant cells for which no critical prepetfatory 

 method has been available previously. 



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