Blood Supply jo 



capillary circulation during activity. Such studies as have been 

 made of the living circulation in the glands do not greatly clarify 

 the issues. Holtzlohner and Niessing (1936a and b) saw a rather 

 sluggish circulation in capillaries around the acini in the resting 

 gland that was greatly slowed or arrested during activity, despite 

 the increased total blood flow through the gland. Briicke and 

 Zwiauer (1938), on the other hand, saw a consistent increase in 

 flow in the acinar capillaries during activity and claimed that a 

 decreased flow was seen only if the digastric muscle was contracted 

 and obstructed secretory outflow. Burgen and Seeman (1958), on 

 the basis of tracer experiments, came to the conclusion that most 

 of the blood perfusing the gland went to capillaries in the duct 

 system and that the flow in these was mainly countercurrent to the 

 flow of saliva. They also give reasons for supposing that there might 

 be serial perfusing of the ducts and acini. These observations are 

 consistent with Kowalevsky's preparations but are not supported 

 by Spanner. It is difficult to see how an active secretion of water 

 by the acini (if this occurs, see p. 195) could be supported in the 

 face of the arrested circulation found by Holtzlohner and Niessing 

 (1936^ and b). 



Further, the observations of Burgen and Seeman do not allow 

 for a very extensive circulation through arteriovenous anastomoses, 

 since this blood would not be available for exchange of solute with 

 the gland parenchyma. It is hard to see how such a circulation can 

 serve a physiological function unless the arteriovenous systems are 

 in line with endocrine cells within the gland. It is possible that the 

 epithelioid cells found by Spanner (1942) are of this type. In any 

 case all observations agree in emphasizing the richness of the 

 vascularization of the duct system both anatomically and function- 

 ally. 



LYMPHATICS 



Little is known of the lymphatics of the salivary glands. Klein 

 (1882) found richly intercommunicating lymphatic channels 

 mainly running along the ducts and surrounding the blood vessels. 

 Extensive lymph spaces are found around the alveoli with inter- 

 connections to adjoining lymph spaces. In the central part of the 

 gland drainage seems to run into the ducts, in the more peripheral 

 part to lymph vessels at the margin of the Lobules. 



