THE SALIVARY GLANDS 387 



The serous appearing cells of the latter form of mucous acinus are 

 frequently arranged as i cj^c_entic ^raups -bordering upon the adjacent 

 mucous cells. Such groups are known as the demilunes (of Heidenhain) 

 or crescents (of Gianuzzi; Fig. 357"). They occur at the periphery 

 of the acinus, their base being applied to the membrana propria, their 

 inner margin sometimes reaching the glandular lumen, but more fre- 

 quently separated therefrom by the overlapping of the adjacent mu- 



FIG. 357. FROM THE SUBLINGUAL GLAND OF MAN. 



a, salivary intralobular duct; e, acinus whose cells contain no mucus; s, mucous 

 acini, at s' with a demilune; sz, mucous cells in .the duct. X 500. (After Kolli- 

 ker.) 



cous cells. The demilunes are frequently found at the blind ex- 

 tremity of the secreting" acinus, but they may also occur along its 

 sides. 



The nature of the demilunes is the subject of considerable discussion. 

 Heidenhain (Arch. mikr. Anat., 1869) first advanced the theory that 

 the mucous cells were destroyed during secretion, and that the function 

 of the demilunes was therefore to replace the disintegrated mucinous 

 cells. This theory has been practically abandoned, for no one has yet 

 demonstrated active cell division in the demilunes, a process which 

 would necessarily be concomitant with the rapid development of mucus 

 from demilune cells. 



Hebold (1879) is responsible for the theory, strongly supported by 



