104 



A. S. Parkes 



type of cell. On storage at the low temperature the cell may 

 be apparently stable, as with bull spermatozoa (Rowson 

 and Polge, 1953) and rat ovarian tissue (Parkes and Smith, 

 1953), or the loss caused by the initial freezing may be 

 increased, as with fowl spermatozoa or human red cells, 

 according to the type of cell, the medium and the temperature. 

 In any case, cells that survive storage have apparently not 

 aged. Frozen bull spermatozoa, for instance, after thawing, 

 survive at normal temperatures as well as do fresh sperm, 



too 



20 40 60 80 100 120 



DAYS AFTER TRANSFUSION 



Fig. 1 . Survival after transfusion of red cells stored at — 79° C. 



for six months and at +4° C. for eleven days. Survival is 



normal. (Mollison, Sloviter and Chaplin, Lancet, 1952, 2, 501. 



By permission of the Lancet.) 



and human red cells, after long periods of storage, have a 

 normal expectation of life in the circulation after transfusion 

 (Mollison, Sloviter and Chaplin, 1952). 



A significant deduction is to be drawn from these observa- 

 tions. It may be assumed that biochemical changes are 

 arrested at the very low temperatures employed. The 

 changes taking place in cells which suffer damage on storage 

 must therefore be physical ones occurring in the absence of 

 the usual biochemical processes of repair. The various factors 

 involved in the case of the red blood cell have been investi- 

 gated in detail by Lovelock (1954), according to whom the 

 damage caused by storage under unfavourable conditions 



I 



