334 



B. NAKIC, A. KASTELAN AND N. AVDALOVIC 



The test was performed four to eight weeks following the 

 operation for parabiosis and cross-grafting and at least two weeks 

 following the last observed immune crisis in the graft. The foreign 

 strain used was AGA black rat obtained from a mutant of a cross* 

 between wild gray male and albino female and now in the F7 

 generation. Destruction of skin homografts exchanged between 

 members of the AGA and Y59 strains is invariably complete 

 within 12 days. 



As shown in Table II, all AGA grafts were destroyed by the 

 14th postoperative day, while second grafts from parabiotic 



Table II 

 Specificity of tolerance induced in Y59 rats following short-term 



PARABIOSIS WITH WiSTAR PARTNERS 



partners were well accepted. There was a good growth of hair, 

 and both the first and second cross-grafts grew in size as the animals 

 gained weight. At the time of rejection of the AGA grafts 

 several punctate necroses were observed in both cross-grafts but 

 healed quickly. Breakdown of tolerance was marked by practi- 

 cally simultaneous rejection of both cross-grafts. 



It is interesting to note the delay with which AGA grafts were 



* Obtained from the Institute "Boris Kidric", Vinca, Belgrade, by courtesy 

 of Dr. P. N. Martinovic. 



