PRINCIPLES AND PRACTICE 

 OF MILK HYGIENE 



CHAPTER I 



PHYSIOLOGY OF MILK SECRETION 



CERTAIN facts concerning the physiology of milk 

 secretion are of importance in milk hygiene. These will, 

 therefore, be briefly presented. 



Udder Structure and Cell Activity* The udder or 

 mammary gland of the cow consists of a large number 

 of alveoli or acini arranged in lobules or groups and 

 held together by connective tissue. The alveoli of each 

 lobule communicate with a common duct which, after 

 emerging from the lobule, continues its course in the 

 interlobular connective tissue toward the milk cistern. 

 The ducts from the several lobules unite to form the 

 larger milk canals. The latter increase in size as they 

 approach the milk cistern, in which they terminate. 

 From the bottom of the milk cistern, a short, narrow 

 canal, called the teat canal, extends through the lower 

 end of the teat to the exterior. The udder of the cow 

 contains four of these glandular systems, one for each 

 teat. Each glandular system is spoken of as a " quarter." 



The alveoli are lined with glandular epithelial cells 

 which, in the actively secreting udder, are separated from 

 the capillaries by only a thin basement membrane. These 

 cells select from the blood circulating in the capillaries 

 certain materials which they convert into those substances 



