Pathology, and Histology of the Mammary Gland. 



comes a depression. From the middle of this depressed area there appears an elevation 

 that later becomes the teat. 



In cattle a single excretory canal enters from the bottom of 

 the mammary envelope (point of the teat), into the tissue (the 

 milk duct), the end of which, the milk cistern, breaks up into the 

 secondary lactiferous ducts. The lower opening of the teat con- 

 tains unstriped muscle fibres which act as a sphincter to prevent 

 the escape of milk. (Meckel, Kolliker, Langer, Bonnet, Profe, 

 Schwalbe, Huss, Gegenbauer, Klaatsch.) 



According to the number of the glandular organs there are 

 distinguished the oligomasts and the polymasts. Cows are nor- 

 mally tetramasts, and usually possess four distinctly separated 

 glandular masses, commonly termed the quarters, from each of 

 which protrudes a long teat. The four quarters are united to- 

 gether in pairs and are arranged symmetrically. Between their 

 bases and the yellow abdominal fascia they have a rich layer of fat. 



The udder is attached along the linea alba to the yellow abdominal fascia, and to 

 the tendons of the abdominal muscles, by two layers of elastic tissue, the suspensory liga- 

 ment (ligamentum suspense rium mammarum) which penetrates the udder between the 

 two halves. 



Although the quarters situated on one side show no visible 

 anatomical separation, injection tests with colored gelatin, and ob- 

 servations in cases of inflammation of the udder in natural and 

 artificial infections have proven that the secretory canal systems 

 of the anterior and posterior quarters are separated in the same 

 way as those of the opposite quarters. 



These canal systems collect into excretory ducts and terminal 

 tubules and finally empty into the milk cistern, which in its upper 

 part is greatly dilated and in its lower part is more constricted. 

 Each quarter possesses a teat (6 to 10 cm. in length) from the milk 

 sinus of which, the duct of the teat (ductus lactifera) of about 8 

 mm. in length, passes to the outside. The entire udder is covered 

 by fine, slightly hairy skin, which extends posteriorly and supe- 

 riorly into the escutcheon or so-called milk mirror. 



The size of the udder varies in the different breeds and indi- 

 viduals. 



In the sheep and the goat there are two milk glands, each possessing a teat which 

 stands out in a divergent direction from the one opposite. Each teat has one excretory 

 duct. While the teats of the sheep are finely haired, those of the goat are hairless. 



The blood vessels of the udder are derived from the branches 

 of the external pudic artery and anastomose with the various 

 venous branches, through which the blood flows posteriorly 

 through the perineal vein into the internal pudic vein and finally 

 into the obturator vein. The greatest part of the venous blood 

 flows laterally into the external pudic vein and anteriorly into the 

 subcutaneous abdominal vein, which forms the immediate continu- 

 ation of the external pudic vein and which is known as the milk 



