64 Innervation of the Glandular Elements 



that the level of supersensitivity attained by treatment with para- 

 sympatholytic agents was higher than that created by cutting the 

 chorda (Emmelin and Stromblad, 1957). The drug had obviously 

 excluded chorda impulses from acting on the gland, but must 

 also have had some further effect. Since the agent used (piperidino- 

 ethyl-diphenyl-acetamide) was found to be highly specific as a 

 parasympatholytic agent it was concluded that the additional sen- 

 sitization, above the chorda level, indicated that the drug had 

 prevented some acetylcholine, unconnected with preganglionic 

 chorda impulses, from acting on the gland. It is reasonable to 

 assume this to be the acetylcholine supposed to leak continuously 

 from the endings of the postganglionic, parasympathetic neurones. 

 If this be true, the experiments described would demonstrate that 

 this acetylcholine normally exerts some action on the gland cells, 

 the elimination of which would manifest itself in a supersensitivity. 

 The postganglionic neurones of the submaxillary gland cannot be 

 completely eliminated surgically since some of them are situated 

 within the gland ; but if the chorda is dissected towards the hilum 

 of the gland and removed as thoroughly as possible, a super- 

 sensitivity is found to follow which surpasses that obtained by 

 section of the chorda but is not quite as high as that found after 

 treatment with parasympatholytic agents (Emmelin, i960). This 

 affords additional evidence of some influence exerted by the 

 postganglionic neurone on the gland. 



The sympathetic, postganglionic neurone seems to have some 

 similar action on the gland cells, for whereas removal of that 

 neurone causes a supersensitivity, preganglionic sympathetic 

 denervation does not (Emmelin and Engstrom, 1960&). 



SECRETORY FIBRES THROUGH LESS-KNOWN CHANNELS 



Several investigators have concluded that some of the salivary 

 glands may receive secretory fibres by other routes than those 

 generally accepted. Seo (1934) cut the chorda tympani and re- 

 moved the superior cervical ganglion in dogs supplied with a per- 

 manent fistula of the submaxillary and sublingual glands. In spite 

 of these operations secretory responses were obtained on feeding 

 and even when food was shown. The effects were small shortly 

 after the nerves had been cut but increased somewhat in the course 

 of time. Various procedures, such as cutting other nerves in the 

 neighbourhood, were tried in order to eliminate the effects, but 



