10 



Anatomy, Pathology and Histology of the Mammary Gland. 



With puberty the alveoli appear in the cow surrounded by strong connective tissue. 

 In older virgin individuals they sometimes show a slight amount of secretion. 



A considerable increase of the glandular tubes appears only 

 after the first conception. The tubes become more dilated and 

 branch more and more, forming alveoli, from which other ducts 

 bud out. 



Although indications of secretions in the cells may not yet be 

 visible, the cavities contain a homogenous or fine granular mass 

 of cells or cell fragments. The gland prepares for the secretion, 

 growing at the expense of the atrophying or expanding connective 

 tissue, until ready to commence its secretion. 



Fig. 5 



Superior portion of the teat canal (a) with a reflection of the cutaneous mucous membrane 



of the cistern (b). 



The cell lining of the larger glandular ducts is of double 

 layers, as in the cistern, while that of the smaller ducts and al- 

 veoli is composed of only a single layer. The epithelium of the 

 latter appears cubical or flat, while the upper layer of the former 

 is cylindrical; in the deep layer the cells are more cubical and 

 rounded, partly wedged in between the bases of the superficial 

 cylindrical cells. The borders of the cells are sharp and the proto- 

 plasma is clear. The nuclei of the epithelia frequently show mi- 

 tosis, that is, division and multiplying forms. The cells rest on the 

 so-called basket cells and the membrana propria. The basket cells 



