Studies on the Function Canine Heat

Abstract

PRESERVATION of erythrocytes and spermatozoa at near-freezing and below-freezing temperatures has proven of great practical usefulness. Freezing of larger biological units—whole organs or intact organisms—has failed as a means of preservation. With thawing as well as freezing, an incompletely understood set of chemical, physical, and mechanical events causes tissue destruction and death.¹From presently available information, one can reasonably hypothesize that below zero temperatures per se are not incompatible with survival and that all lethal damage occurs with the transition between unfrozen and frozen states. A corollary of this hypothesis would be that tissue survival would be possible if only a means for instantaneous freezing and rewarming were available. Indeed, the technical impossibility of such rapid freezing has long been recognized as the central obstacle to freezing of more than very minute pieces of tissue. The studies reported here are an attempt to sidestep the freezing dilemma—to reap the