698 DISEASES OF THE MAMMARY GLAND. 



by introducing the finger, or a sponge tent, or by injections of warm 

 water, but in some subjects dilatation can only be effected by the 

 cautious use of a sound. 



V.— DISEASES OF THE MAMMARY GLAND. 



The mammary gland comprises parenchyma and stroma. The 

 formation of the former is partly vesicular, partly tubular. In the con- 

 nective tissue of the stroma lie variously- shaped spaces, the gland vesicles 

 or acini, which open into the lactiferous canals or gland ducts. Both 

 are lined with cylindrical epithelium, and together form the milk- secreting 

 tissue. The milk flows thence into the milk ducts or collecting canals, 

 to pass either directly outwards through the teat (man and carnivora), 

 or in herbivora, into a cavity at the base of the teat, termed galactophorous 

 sinus or milk cistern. In ruminants the udder has only one galactophorous 

 sinus and teat for each division or " quarter " ; but in the mare's udder 

 each teat is supplied by two or more sinuses. From the galactophorous 

 sinus a narrow canal (teat duct), lined with mucous membrane, leads to 

 the exterior, and in the mare two of these exist in each teat, in ruminants 

 only one. In swine, each teat has two, sometimes three ducts, in com- 

 munication with as many small milk cisterns. In herbivora, then, each 

 teat corresponds to a particular division of the udder, in the cow, to a quarter, 

 in the ewe and the goat, to one half of the udder. In carnivora the divisions 

 of the udder (ten in the bitch), are, externally, not so sharply bounded, 

 and each is connected with the six or more openings on its corresponding 

 teat. The cat has eight glands and two orifices on each teat. 



Each gland, independently of the modified skin that forms the external 

 covering, is surrounded by a capsule of fibro-elastic tissue, which supports 

 and assists in holding the gland in position. This capsule is reinforced 

 in places by suspensory bands which are connected on each side with the 

 tunica abdominalis. Externally it closely adheres to the skin ; in the 

 mesial plane it is confounded with the capsule of the opposite gland ; and 

 internally it furnishes numerous intercrossed septa, which pass into the 

 substance of the gland, dividing it into lobules and lobes more or less 

 distinct. 



A double system of lymph vessels exists in the udder ; the one lying 

 near the surface arises from the capsule, and is connected with the lymphatics 

 of the skin ; the other invests the acini, which are surrounded by fine 

 lymph vessels. Furstenberg distinguished between the surface lymph 

 vessels arising close under the skin, which pass into the depths along with 

 the chief veins, and those which arise from the plexus in the interior of 

 the gland, and accompany the deeper-lying venous branches. Furstenberg 

 held that during lactation the lymph vessels appear to be distended with 

 lymph. He also succeeded in filling them with air from the milk ducts, 

 and discovered a valvular arrangement in them. 



The retro-mammary lymphatic glands are two in number, and are 

 situated above the posterior quarters, outside the capsule of the glands 

 and close to the perineum. The superficial collecting vessels are dispersed 

 under the skin and anastomose with one another on the surface of the 

 gland, the anastomosis being most intimate between those of the same 

 quarter, finally emptying separately by two large channels into the retro- 



