546 THE KEPRODUCTIVE SYSTEM 



epithelium is similarly massed into a double layer of small cells. The 

 lobules are reduced in size and consist only of a few shrunken alveoli 

 clustered about the termination of an interlobular duct. The lumen of 

 the alveoli, if any, contains no secretion, and that of the ducts, except 

 for a little granular albuminous material and an occasional leukocyte, 

 is empty. 



The connective tissue stroma is much increased in volume, and in 

 places shows a marked infiltration with fat. The alveolar tissue of the 

 mammary gland at all times contains wandering leukocytes, and many 

 granule cells, both acidophil and basophil in character. 



With the appearance of pregnancy the gland promptly reenters a 

 state of activity; its alveoli multiply; its connective tissue becomes rela- 

 tively diminished in volume; its lobules are reformed and their alveoli 

 finally begin ' secretion, a process which is heralded by the formation of 

 a granulo-fatty colostrum, a rather serous fluid in which are suspended 

 large numbers of colostrum corpuscles, large spheroidal cells, resembling 

 leukocytes in their general form and in the character of their nuclei, but 

 which possess a broad rim of cytoplasm often containing numbers of fat 

 globules of varying size. Their cytoplasm has also been shown to contain 

 neutrophil granules of Ehrlich similar to those of the polymorphonuclear 

 leukocytes (Michaelis, Arch. mikr. Anat., 1898). 



Colostrum discharge precedes and follows the period of lactation for 

 a few days ; it appears also in both sexes for several days after birth when 

 it is commonly known as 'witch's milk/ 



The origin of the colostrum corpuscles is still somewhat in doubt, 

 though modern technic has gradually discredited the theory of their 

 origin from desquamated remnants of the alveolar epithelium, and shows 

 them to be more probably enlarged leukocytes which have wandered 

 through the alveolar wall and have thus found their way into the 

 lumen, where they take on a phagocytic activity and continue their 

 growth. The following facts may be mentioned in support of this theory : 

 a, leukocytes can be readily found between the cells of the alveolar 

 epithelium as well as in the lumina of the saccules; I, the colostrum 

 corpuscles examined in a fresh condition on a warmed slide have been 

 repeatedly shown to possess the property of ameboid motion; c, the 

 colostrum corpuscles, when stained, present the same granular and non- 

 granular varieties as do the leukocytes of the blood; d, finally, the 

 colostrum corpuscles have been shown to undergo mitotic cell division 

 (Bizzozero and Ottolenghi), a phenomenon which we should hardly ex- 

 pect to find in degenerated and desquamated epithelial cell remnants. 



