180 ELEMENTS OF HISTOLOGY. [Chap. xxn. 



239. The framework. Each salivary gland 

 is enveloped in a fibrous connective tissue capsule, 

 in connection with which are fibrous trabeculse and 

 septa in the interior of the gland, by which the sub- 

 stance of the latter is subdivided into lobes, these 

 again into lobules, and these finally into the alveoli 

 or acini The duct, large vessels and nerves pass 

 to and from the gland by the hilum. The con- 

 nective tissue is of loose texture, contains elastic 

 fibres, and, in some instances more, in others less, 

 numerous lymphoid cells. In the sub-lingual gland 

 they are so numerous that they form continuous rows 

 between the alveoli. The connective tissue matrix 

 between the alveoli is chiefly represented by fine 

 bundles of fibrous tissue, and branched connective 

 tissue corpuscles. 



240. The ducts. Following the chief duct of 

 the gland through the hilum into the interior, we see 

 that it divides into several great branches, according 

 to the number of lobes; each of these breaks off 

 into several branches, one for each lobule. Entering 

 the lobule the duct has become very minute, and 

 passing along it gives off" laterally several minute ducts, 

 all within the lobule being the intralobular ducts, 

 or the salivary tubes of Pfliiger, the bigger ducts 

 being the interlobular, and, further, the interlobar 

 ducts. Each of the latter consists of a limiting 

 membrana propria, strengthened, according to the 

 size of the duct, by thicker or thinner trabeculse of 

 connective tissue. In the chief branches there is pre- 

 sent in addition non-striped muscular tissue. The 

 interior of the duct is a cavity lined with a layer of 

 columnar epithelial cells. In the largest branches there 

 is, outside this layer and inside the membrana propria, 

 a layer of small polyhedral cells. 



241. The intralobular ducts, or the salivary 

 tubes of Pfliiger, consist of a limiting membrana 



