Preservation of Tissue in vitro 



1G7 



work on the isolated uterus of the ^uinea pig, survival after 

 freezing in various media for various times being assessed by 

 its spontaneous contractions and its responsiveness to hista- 

 mine. Conditions for complete survival have not yet been 

 determined, but a considerable degree of reactivation is 

 compatible with freezing by present methods, and the 

 damage is not increased by storage (Parkes and Smith, 1954). 

 It is likely that present methods with the isolated uterus can 

 be much improved and applied to other organs, so that a 



Fig. 5. Contractility of isolated uterus of guinea pig after 



storage for tliree months at — 79°C. in 20 per cent glycerol- 



Ringer. Figures indicate fig. of histamine added to bath. 



Contractility is subnormal but still vigorous. 



great extension of experiments involving variation in the 

 age of the part in relation to the age of the whole can be 

 envisaged. 



The Whole Body 



The work outlined above naturally turned our attention 

 to the problem of cooling the whole animal to such an extent 

 as to arrest all vital processes and confer upon it, in a state 

 of suspended animation, the kind of comparative immortality 

 which can now be effected with bull spermatozoa and other 

 cells appropriately frozen and maintained at —79° C. 



Any such project obviously presented enormous difficulties, 

 })articularly in view of the different requirements for safe 

 freezing of different types of cell and of the overriding neces- 



