THE PHYSIOLOGY OF LACTATION 35 



globules are released small particles of cell protoplasm frequently 

 adhere, forming "caps" on the fat globules. 



The role played by the cells of the alveoli may be one of the 

 following: 



1. The cells are converted into secretion. 



2. Secretion is formed without alteration of the cells, so that 

 secretion is not an essential part of the cell. 



3. Part of the cell is converted into secretion, but the cell 

 itself is regenerated. 



The histologic condition ©f the normal milk-secreting gland 

 changes up to the period of active secretion. The normally clear 



Fig. 10. — Corpuscles of Nissen (Ernst). 



protoplasm becomes turbid, the cells appear not to be clearly sep- 

 arated, the nuclei enlarge, and mitoses are frequent. During the 

 process small fat globules can be seen and several globules adhere, 

 forming masses. Finally, the products of cell metamorphosis are 

 discharged into the lumen of the milk-ducts. Leukocytes and 

 other body cells assemble in large numbers near the milk-secreting 

 glands and are discharged with the secretion. At the end of lacta- 

 tion a condition resembling the normal condition is restored. 



The nuclei of epithelial cells undergo a transformation from 

 which the "corpuscles of Nissen" (Fig. 10) appear. The chroma- 

 tin assembles near the periphery of the nucleus and forms homo- 

 geneous, sickle-shaped bodies. A translucent ring is formed around 



