240 



HISTOLOGY 



being pseudostratified, with two rows of nuclei (cf. Fig. 39, p. 49). Pos- 

 sibly the epithelium near the outlet of the duct is also pseudostratified. 

 This excretory portion of the duct is followed by the secretory part, formed 

 of simple columnar cells with basal striations, perhaps indicative of secre- 

 tory activity (Fig. 231). As shown in the diagram (Fig. 232) and in the 

 section (Fig. 233) the secretory ducts become slender, forming the inter- 

 calated, ducts. These are lined with flat spindle-shaped cells which are 

 continuous with the large cuboidal serous cells of the terminal alveoli. 

 The gland cells when empty of secretion are small and darkly granular, 



FIG. 234. SECTION OF THE PAROTID GLAND FROM A MAN OF TWENTY-THREE YEARS. X 100. 



Portions of three lobules are shown, which have drawn apart from one another in the process of preparation. 



Note the abundance of secretory ducts. 



and when full are larger and clearer. They rest upon a basement mem- 

 brane containing stellate cells. Intercellular secretory capillaries end 

 blindly before reaching the basement membrane. 



Between the alveoli, which are somewhat elongated and branched, 

 there is vascular connective tissue containing fat cells. In denser form 

 it surrounds the lobules and lobes of the gland, and the larger ducts. The 

 ducts which are found in the connective tissue septa are called interlobular 

 ducts, in distinction from those which are surrounded by the alveoli in 

 which they and their branches terminate. The latter are intralobular 

 ducts. They are smaller and have less connective tissue around them than 

 the interlobular ducts, of which, however, they are continuations. 



