The Grafting of Tissues 



PRACTICAL VAIA'K IN KKPAIRIN(i TllK WOUNDED OH DISKASHD HUMAN 



BODY.— THKORETICAL VALUE, AND SOME OF THE FACTORS WHICH 



CONTROL SUCCESSFUL TISSUE TRANSPLANTATION 



]^y L E O L E B 



Professor of Coniparative Patliology, Washington University Medical School, Saint Louis 



THE graftino- of plant tissues is 

 a well-known and practiced 

 custom, one which has become 

 so important that should the practice 

 be discontinued, the present high grade 

 of our fruit orchards, for instance, 

 would completely disappear. Some re- 

 markable results have been produced 

 experimentally, such as the grafting of 

 the nightshade on to the tomato. The 

 great value, however, lies in the exact- 

 ness with which cultural varieties can 

 be propagated without the serious loss 

 of type characters that inevitably fol- 

 lows from reproduction by seed. All of 

 us are doubtless familiar with the re- 

 sults obtained by grafting a young twig 

 of the double rose on to the root of the 

 wild variety, obtaining thereby the 

 l)oanty of the former and the hardiness 

 of the latter. 



In graftiiig animal tissues, trans- 

 ]ilantations succeed better among the 

 lower animals than in higher classes, 

 just as the regenerative power for in- 

 jured or lost parts is on the whole 

 greater in the lower forms. The more 

 complex the organism, the more diffi- 

 cult it is to accomplish the transplanta- 

 tion successfully, the more must the 

 various factors which control the phe- 

 nomenon be carefully studied. Because 

 of the very practical importance in re- 

 placing lost or injured tissues in man, 

 much study and experimentation have 

 been conducted by scientists in order 

 to understand the process most thor- 

 oughly, and as a result of these studies 

 much has been learned. 



Grafting of tissues is a procedure 

 used bv the surgeon in cases in which 



there are defects somewhere in the body 

 which are very extensive. Without 

 grafting, such defects either would not 

 heal at all or they would leave a scar 

 whit'li might threaten to interfere with 

 the normal activity of the body. Dur- 

 ing the last four years, in dealing with 

 the ravages of war on the human body, 

 even the features of the face have been 

 built up of grafted tissues in many in- 

 stances. Defects in the skin are per- 

 haps most frequently treated by graft- 

 ing; but grafting of bone, tendon, 

 fascia, and fat tissue is resorted to in 

 certain cases. 



It is therefore of great practical in- 

 terest to analyze the factors on which 

 successful grafting (transplantation) 

 of tissues depends. 



But of much greater importance is 

 perhaps the theoretical interest that 

 attaches to grafting of organs. The 

 experimental method permits us to 

 place a tissue under conditions which 

 differ from those under which it lives 

 normally. We can vary such condi- 

 tions at will and thus we can obtain an 

 insight into the factors which deter- 

 mine the life and growth of tissues in a 

 normal as well as a pathological state. 

 It is a mode of investigation which 

 brings us in touch with the deepest 

 problems of biology and pathology, 

 namely, factors determining growth 

 and life itself. Many diseases are 

 caused by abnormalities in growth of 

 various tissues. In diseases of the 

 heart, liver, kidney, pancreas, thyroid, 

 and other organs, abnormalities of tis- 

 sue growth are often the underlying 

 factor. 



701 



