GLANDS 143 



BRANCHED TUBULAR GLANDS 



With the branching of the duct-portions of gland-tubules, 

 usually occurs a dilatation of the extremities into acini or alveoli, 

 although pure examples of branched tubular glands are afforded in 

 the gastric and uterine glands. 



The most nearly typical branching of gland -like tubules is 

 afforded by the tubuli uriniferi of the kidney, or the system of 

 tubes in the testicle. The tubules here present other features 

 peculiar to them, which will be referred to under the proper head. 



ACINOUS GLANDS 



The dilatation of branching tubules, referred to under the 

 previous heading, results in the formation of acinous glands. 

 They are formed by the subdivision of a main tube or duct, with 

 repeated branching of the secondary tubules. Collections of ter- 

 minal branches often result in globular masses, which are more 

 or less perfectly isolated from one another by connective tissue. 

 In this way compound acini are produced, such as the pancreas, 

 the salivary, mammary, and buccal glands. 



The large compound acinous glands are also called compound 

 racemose glands. Simple acinous glands do not occur in human 

 tissues. 



THE PAROTID GLAND 



The parotid, submaxillary , sublingtial,3ind. bitccal salivary glands 

 are typical glandular structures, with individual peculiarities only 

 in respect to the cell-elements ; these vary according to the nature 

 of the secretion formed in each. 



The parotid is a compound acinous gland, leading from which 

 is a principal duct lined with tall columnar cells which collects 

 the fluid saliva from the different divisions of the organ. 



As the duct penetrates the gland it branches freely, the lumina 

 becoming smaller and the cells shorter as thQ deeper parts are 

 approached. 



Each terminal duct is in connection with several acini. The 

 connective tissue adventitia of the duct becomes the thin wall of 

 the acinus, and the lining cells broaden, frequently become poly- 



