THE SKIN. AND ITS APPENDAGES. 



77 



of the three later stages a localized and invading hypertrophy of 

 the cells of the glandular tissue may take place. In this manner 

 cancer is produced. The part played by the lymphatics, which 

 are situated in the mesoblastic tissue of the gland, in the spread 

 of this disease, makes their study important. 



II. Origin of the Capsular or Mesoblastic Part of the 

 Gland. — As the glandular buds grow out into the subdermal meso- 

 blastic tissue, which reacts and hypertrophies around the invading 

 processes, they divide it (see Fig. 58) into (a) superficial, and (b) 

 deep layers, these being joined together by (c) interstitial septa. 

 The superficial and deep layers are fused in (d) the circum- 

 mammary tissue in which the final glandular buds terminate. 

 The processes as they grow outwards also take on (e) perilobular 

 and periductal sheaths. The deep and superficial layers are also 

 connected with the anterior sheath of the pectoral muscles and the 

 skin — for they are all parts of the same subdermal or sub- 

 cutaneous mesoblastic layer. 



subcutaneous lymph, 

 superficial mammary 



'ymphatics of nipple 



subcutaneous 

 ■periductal 



peri-lobular 

 m:perfic. mam. 



circum-mammary 



offer, o, 



vessels j» ■..■■,- 



pectoralis major 



retro-mammary 



Fio. 58.— Diagrammatic Section of the Breast to show the arrangement of its Capsule 

 and Lymphatics. The lymphatic vessels are represented by thin wavy lines. 



Lymphatics. — As each part of the capsule carries a network of 

 lymphatic vessels, into which the glandular lymph passes, it will 

 be seen that the arrangement of the parts of the capsule is 

 an important matter in both the physiology and surgery of the 

 gland. The periductal and perilobular lymphatics communicate 



