SALIVARY GLANDS 



305 



type. The larger ones are constructed in the same manner, the 

 larger number of their secreting alveoli or acini arising through a 

 more complex duct system. 



FIG. 248. CORROSION MODEL OF AN INTERLOBULAR DUCT AND ITS BRANCHES, FROM THE 



HUMAN SUBMAXILLARY GLAND. 



C, intcrlobular duct; Z>, large intralobular duct; E, small intralobular duct; ^inter- 

 calary duct, x 12. (After Flint.) 



The larger ducts of the gland are lined by columnar cells, 



which, as they approach their termination, become superposed 



and thus offer a gradual transition to the stratified epithelium 



upon whose surface they open. The epithelium rests upon a base- 



21 



