4 MASTITIS OF THE COW 



sequence of this lessened nervous stimulation of the gland 

 cells and decreased nutrition a condition of diminished 

 milk secretion results. 



The quantity of milk is greatest during the first month 

 after parturition but gradually decreases afterward. The 

 udder decreases in circumference as it is no longer distended 

 with milk and becomes small and quiescent or in the dry or 

 alactiferous state. 



In consequence of the diminished work and nutrition the 

 organ undergoes a process called atrophy in pathology but 

 which is physiological in this case. The cell elements be- 

 come smaller and their number decreases, since part of the 

 cells become retrogressively altered, fatty degenerated and 

 desquamated. The tubules and consequently the lobules 

 become smaller in this way. At the same time, as an indi- 

 cation of retrogressive alterations, great numbers of leuco- 

 cytes emigrate to the intralobular connective tissue where 

 they assist in the work of absorption. 



The atrophic gland cells give off other products of 

 secretion. This secretion is no longer normal milk, it is 

 grayish-yellow and tliin, not infrequently viscid and con- 

 tains a large quantity of albumin so that it coagulates on 

 boiling. Moreover it is rich in cells, epithelial cells and 

 especially in emigrating leucocytes which are often laden 

 with fat droplets. The secretion is resorbed for the most 

 part, in which work the leucocytes are directly responsible 

 as they re-enter the blood-vessels laden with fat droplets. 

 The atrophic gland cells are capable of producing a yellow 

 coloring matter within their structures which lends a dis- 

 tinct dark yellow color to the cut surface of the yellow 

 udder (yellow atrophy). 



At the next parturition the condition is immediately 

 changed. The cells become stimulated to secretion and the 

 atrophic udder is again well nourished with blood, conse- 

 quently the cells very quickly become functionable again 

 and the milk, especially, very soon becomes normal. The 



