THE STRUCTURE OF THE SALIVARY GLANDS. 



281 



the large cells and the membrana propria. The intralobular ducts are 

 lined by a single layer of large cylindrical epithelium. As is shown in 

 Fig. 1 1 6, E, the nucleus occurs about the middle of the cell, while the 

 outer half, i.e., next the basement membrana of the cell, is finely striated 

 longitudinally, which is due to fibrillsB ; the inner half next the lumen is 

 granular. The intermediary part is narrow, and is lined with a single 

 layer of flattened cells, each with an elongated oval nucleus. There is 

 usually a narrow " neck," where the intralobular duct becomes continuous 

 with the intermediary part, and here the cells are polyhedral (Klein). 



The acini, or alveoli, are the parts where the actual process of secretion 

 takes place. They vary somewhat in shape some are tubular^ others 

 branched, some are dilated and resemble a Florence flask, and several 

 of them usually open into one intermediary part of a duct. Each 



Fig. 116. 



A, duct and acini of the parotid gland of a dog ; B, acini of the sub-maxillary 

 glandjof a dog ; c, refractive mucous cells; d, granular half-moons of Gianuzzi; 

 C, similar alveoli after prolonged secretion; D, basket-shaped tissue investment 

 of an acinus; E, transverse section of an excretory duct lined with cylindrical 

 "rodded" epithelium; F, entrance of a non-medullated nerve-fibre into a 

 secretory cell. 



alveolus is bounded by a basement membrane, with a reticulate structure 

 made up of nucleated, branched and anastomosing cells, so as to resemble 

 a basket (D). There is a homogeneous membrane bounding the 



