Staff of the Cancer Research Genetics 

 Laboratory, University of California 



APPENDIX VII 



Current Applications of a Method of Transplantation of 

 Tissues into Gland-free Mammary Fat Pads of Mice 



A technique for the removal of host mammary gland elements before they penetrate 

 deeply into the mammary fat pad has been developed in our laboratory. ,The re- 

 mainder of the fat pad is then available to receive tissue transplants. The procedure, 

 already published, is as follows: "[The inguinal (number 4) fat pads of] 3-week-old 

 C3H/He Crgl females . . . [were] cleared of host mammary gland elements by means 

 of the following surgical procedure (figure 93). The anesthetized mouse was pinned, 

 ventral side up, on a cork board and scrubbed with 70 per cent ethanol. An inverted 

 Y-shaped incision was made along the abdominal midline and laterally between the 

 fourth and fifth nipples midway down each hind leg. One at a time the resulting 

 skin flaps, with the number 4 mammary gland attached, were carefully separated from 

 the body wall by blunt dissection. The free edge of the skin flap was then pinned 

 to the cork board, exposing the nipple area and most of the number 4 fat pad. In a 

 3-week-old female C3H mouse the mammary gland elements consist of short branching 

 ducts which extend from the nipple area into the fat pad as is shown in figure 94. 

 The nipple area and the large blood vessels ventral to the lymph node and between the 

 fourth and fifth pads were cauterized (figure 94). The area containing the growing 

 gland elements, including the adjacent portion of the fat pad and the surrounding 

 loose connective tissue, was then excised with fine scissors (figure 94) . The remaining 

 portion of the fat pad with its circulation intact and without host mammary tissue 

 was then ready to receive a transplant, or the skin flap was sutured and the transplanta- 



565 



