Breast and Nipple 203 



which processes pass off to blend with the skin, whilst others enter 

 the gland, marking it out into separate lobes. Fat occupies the inter- 

 vals between the lobes, and thus it happens that large fat breasts may 

 be of less physiological value than those of a thin woman. A branch 

 of a milk-duct enters each lobe, sending off ramifications which are 

 connected with the small lobules. The ultimate lobule consists of 

 terminal expansions of the ducts into alveoli lined with cubical epi- 

 thelium, and surrounded with branches of blood-vessels, nerves, and 

 lymph-sinuses. As the duct approaches the surface the epithelium 

 becomes squamous. Chronic inflammation of the nipple and prolifera- 

 tion of its epithelial covering (eczema of the nipple} is often the starting 

 point of cancer of the breast. Squamous epithelioma is the nature of 

 the malignant growth in these cases, and it may eventually implicate 

 the entire gland. 



The ducts descending from the nipple radiate through the gland, 

 and when an incision is made into the breast the scalpel should be 

 directed straight from the centre towards the periphery, so that it may 

 pass between and not across the ducts. During lactation a milk-duct 

 may be so distended with milk as to form a large tumour, galactocele ; 

 the condition is like an encysted hydrocele of the testis. 



Supply. The mammary arteries and veins are branches of the 

 long thoracic and other offsets of the axillary trunks, and of the internal- 

 mammary. The aortic intercostals also help in the supply. 



Of the lymphatics, some few, from the inner side, pass between the 

 costal cartilages to enter the mediastinal glands; the others pass along 

 the border of the pectoralis major into the axillary glands. 



The nerves come from the lateral cutaneous branches of the inter- 

 costals, and from the endings of the intercostal nerves themselves. 



It has been suggested that the mammae are but modifications of 

 sebaceous glands, and sometimes during pregnancy enlargement of the 

 sebaceous glands in the axilla may be discovered, representing supple- 

 mentary mammas. Occasionally additional mammae and nipples exist, 

 either in the pectoral region or down the front of the abdomen. 



In sdrrhus mamma a heterologous growth of fibres and cells forms 

 a hard mass, generally upon the axillary side of the nipple. The 

 malignant infiltration extends along the fibrous processes which 

 attach the gland to the surrounding tissues, and so the mass becomes 

 connected with the skin, the pectoral muscles, the chest, and even 

 with the pleura. Subsequently the new fibrous tissue atrophies, so 

 that the skin is dimpled and the nipple retracted. 



Before the nipple is actually retracted it may show a slight but 

 highly suspicious deviation from its normal inclination. Retraction of 

 the nipple may also be due to atrophy of the new fibrous elements left 

 after chronic inflammation, corresponding to the contractions described 

 in cirrhosis of liver. The cut surface of the scirrhous mass becomes 

 concave on account of the further contraction of the fibrous tissue. 



