STUDIES ON CHEEK POUCH SKIN HOMOGRAFTS 

 IN THE SYRIAN HAMSTER* 



R. E. BiLLINGHAM AND WiLLYS K. SiLVERS 

 The Wistar Institute of Anatomy and Biology, Philadelphia 



The existence of "privileged" or favoured sites in the body, in 

 which grafts of hving tissue of foreign origin may long be 

 accepted by the host, apparently exempted from the usual 

 immunologically procured rejection process, is well established. 

 Familiar examples are the brain, the anterior chamber of the eye, 

 the substantia propria of the cornea, and possibly the testis (see 

 Medawar, 1948; Billingham and Boswell, 1953; Russell, 1961). 

 The uniqueness of each of these sites seems to depend upon the 

 fact that the physiological pathways necessary for either the 

 evocation or the putting into effect of an immunological response 

 are incomplete in some respect — i.e., there is a break in either the 

 afferent or efferent pathways of the immunological reflex. 



The multiplicity of reports of the successful transplantation of 

 tissues, normal and malignant, of both homologous and hetero- 

 logous origin, to the cheek pouch of the Syrian hamster [Mcso- 

 cricctus auratus), where they rapidly acquire a rich blood supply 

 and may thrive for considerable periods (see Lemon et ah, 1952; 

 Cohen, 1961; Yohn ct ah, 1962), constitute a strong prima facie 

 case that this, too, is an immunologically privileged site. 



Confirmatory evidence of a more direct nature has been forth- 

 coming from studies in which the fates of skin homografts or 

 skin heterografts implanted into the connective tissue of the wall 



* This work was supported in part by a U.S.P.H.S. Research Grant (C-5927) 

 and in part by Grant (DA-CML-18-108-61-6-13) from the U.S. Army Chemical 

 Research and Development Laboratories, Army Chemical Center, Maryland. 



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