PUESEIIVATION OF TlSSUE iu vltt'o 1G5 



arises from tlie failure of bioeliemieal processes to rei)air 

 biophysical dissolution. With the red cell it appears that 

 damage of sub-lethal degree occurring during storage may 

 be repaired when the cell is returned to its normal environ- 

 ment. It is possible that the general thesis set out by Lovelock 

 is of more general applicability to the exhaustion and repair 

 of cells; it might perhaps be possible to regard ageing as the 

 result of increasing failure to repair by active biosynthesis 

 the passive dissolution due to biophysical causes. 



Isolated Tissues 



I want to turn now to the application of this work to the 

 study of the ageing of parts in relation to the whole. I have 

 already indicated that ovarian tissue of rats can be preserved 

 for long periods in liquid air at —190° C, that there is some 

 loss of cells on freezing and thawing, but that the loss is not 

 increased on storage and that the cells which survive have 

 not apparently aged. Details of technique and data for 

 tissue frozen for up to one year were given at a previous 

 symposium (Smith and Parkes, 1954). By the time similar 

 material had been frozen for two years a number of complica- 

 tions had appeared. For one thing, several of the donor rats 

 died during the second year. For another, several known 

 failures in the maintenance of the flasks of liquid air had 

 occurred, and tissue known to have warmed up had been 

 discarded. As a result of these circumstances there was avail- 

 able after approximately two years a number of old ovariecto- 

 mized females without corresponding stored ovaries as well as 

 stored ovaries without corresponding old animals. An experi- 

 ment was therefore designed in which in addition to the auto- 

 grafting of long-stored ovaries, fresh ovarian tissue from young 

 females was homografted into old ovariectomized females 

 and long-stored ovaries into newly ovariectomized young 

 females (Table I). The results of the first experiment sug- 

 gested that the tissue autografted after storage for approxi- 

 mately two years (line one of the table) did not take well. 



