The individual effects of liquid nitrogen and freeze-dry storage on several dehydrogenase reactions in tissue sections

Abstract

Summary The effects of liquid nitrogen storage on the enzyme histochemistry of tissue sections obtained from 12 specimens of human and animal tissues were evaluated by employing histochemical reactions for six dehydrogenases. Comparisons were made of these enzyme activities in serial sections of tissues which had been in liquid nitrogen for only a few hours with the serial sections of the same tissues which had been stored in liquid nitrogen up to 6 months. Comparisons were also made between serial sections which had been in liquid nitrogen for a few hours and those which had been freeze-dried after this initial exposure to liquid nitrogen. It was found that the liquid nitrogen storage of tissue sections did not appreciably alter the activity or pattern of the six enzymes studied, but that the process of freeze-drying, after