Blood Supply 15 



secretion and pancreozymin on zymogen release is widely accepted ; 

 in the salivary glands a similar dualism is operating even though 

 the effector agent may be common to the two processes. 



BLOOD SUPPLY 



The vascular architecture of the salivary glands presents many 

 unusual features whose physiological significance is enigmatic, but 

 may provide clues to the equally strange behaviour of the gland 

 blood flow during activity (see Chapter VII). 



The main arteries to the submaxillary and sublingual glands 

 enter at the hilus although additional minor arteries may enter on 



Throttle vein - 

 (relaxed) draini 

 from the venous 

 plexus of a duct 



Hilum a-v anastomosis 



Excretory duct 



Fig. 2.5. General arrangement of vessels in the submaxillary gland, based on 

 injection preparations of the human and guinea-pig glands. 



Note the throttle vein leaving the venous plexus around the duct and entering the ring vein. 

 Note also the arteriovenous anastomoses in the hilus and in the lobules (Spanner, 1937). 



the gland convexity. In the case of the parotid the "hilus" is not 

 such a well-defined entity nor is the position of entry of the arteries. 

 In all the glands the main vessels travel in company with the inter- 

 lobular ducts into the lobules. The vascular territories of the 

 lobules are quite distinct (Fig. 2.5). Within the lobules the arteries 

 continue to travel with the ducts and break up into a very rich 

 capillary plexus around the ducts (Fig. 2.6) (Kowalevsky, 1885; 



