DISCUSSION III 



different hamster strain combinations. It certainly occurred to us at an 

 early stage that a battery of hamsters bearing long-estabUshed cheek 

 pouch skin homografts might provide the basis of a simple all-or-none 

 test for revealing the presence of transplantation antigens in extracts of 

 tissues prepared from the donor strain of the pouch skin grafts. 



Voisin: There is another membranous tissue which is extremely 

 interesting in this respect: dura mater. We started to study it with Dr. 

 Klement, a Russian surgeon who came to work with us. Unfortunately 

 the experiments were not completed. All I can tell is the general trend 

 of the results : in rabbits dura mater seemed to be unable to sensitize the 

 homologous host to a further skin graft from the same donor. Ortho- 

 topic homografts of dura mater were able to remain for long periods of 

 time and they did not sensitize against subsequent skin grafts from the 

 same donors. This tissue seems to behave somewhat like the pouch 

 skin of the hamster. 



Billingham: As soon as evidence was obtained suggesting that the 

 phenomenon we were studying might depend upon peculiar properties 

 of the connective tissue of the cheek pouch skin we started to look for 

 evidence of other types of skin that might have similar properties. 

 Histologically human foreskin bears some resemblance to cheek pouch 

 skin and there has been at least one claim that homografts of foreskin 

 from newborn infants Hved for a surprisingly long time. Critical re- 

 evaluation of this possibiHty might be worth while. Since the thin skin 

 of the scrotum in the rat also bears some resemblance to cheek pouch 

 skin, we tested the fate of homografts of this tissue but found them to 

 be rejected in the usual manner, 



Medawar: Does amnion behave in the same way as pouch tissue ? 



Silvers: We have tried a few experiments with amnion but un- 

 fortunately we haven't had any success. However, this may be due to 

 lesions in the amnion since it is extremely difficult to prepare sheets of 

 this tissue. It certainly deserves further investigation. 



Michie: Can you heterograft hamster "slime" (areolar tissue) and 

 then use it for a matrix on which to do a homograft ? 



Silvers: We have transplanted hamster cheek pouch to rats, and it is 

 not accepted. 



Feldman: I was very interested in your observations of the skin of the 

 hamster cheek pouch. The only other example of which I am aware of 



