566 



APPENDIX 



tion carried out at a later date. The vascularization of the mammary fat pad in the 

 C3H/He Crgl mouse has been investigated by Soemarwoto and Bern, 1255 whose studies 

 indicate that the number-4 fat pad normally has three separate blood supplies and that 

 the surgery described herein did not interfere with the circulation of the remaining fat 

 pad. 



Fig. 93. Drawing of a three-week old female C3H/He Crgl mouse prepared for the 



REMOVAL OF THE MAMMARY GLAND ELEMENTS FROM THE RIGHT NO. -4 (INGUINAL) FAT PAD. 225 



A. Nipple area; B. Right no. -4 fat pad; C. Right no. -5 fat pad. 



"The transplantation site was prepared by forcing the closed points of a fine 

 forceps into the center of the fat pad. The tissue to be transplanted was inserted 

 into the transplantation site, with the use of the same fine forceps. The remaining 

 number-4 fat pad was then similarly exposed and cleared and received a second trans- 

 plant. . . . Finally, both skin flaps were returned to their normal positions, and the 

 incision was closed with wound clips." 255 



The fate of individual tissue areas selected from the mammary gland can be 

 followed by this transplantation method. Pieces of transplanted normal mammary 

 tissue grow out to fill the fat pad with normal mammary gland (figure 95). Trans- 

 plants of hyperplastic alveolar nodules, on the other hand, fill the fat pad with an 

 outgrowth which is hyperactive with regard to the hormonal state of the host (figure 

 96) . With the use of this technique, we have already reported the more frequent 

 development of mammary tumors from transplanted hyperplastic alveolar nodules 

 than from normal mammary gland similarly transplanted, 255 thus directly and decisively 

 establishing the precancerous nature of the hyperplastic alveolar nodule. 



The development of this method has allowed us to begin the analysis of a variety 



