104 Effects of Denervation 



gradually to lose about 30 per cent of its weight in the course of 

 some weeks. It is interesting to find that a similar, or even more 

 pronounced, atrophy occurs after hypophysectomy or adrenalec- 

 tomy (Kahlson and Renvall, 1956). 



The atrophy following section of the chorda is reversible ; after 

 regeneration of the chorda fibres the gland regains its previous 

 weight (Emmelin, Muren and Stromblad, 19570). It has been 

 observed that many changes in the gland due to section of the 

 chorda can be prevented or abolished by prolonged administra- 

 tion of a secretory agent such as pilocarpine (Emmelin and Muren, 

 19500, 195 10, 1952; Emmelin, Jacobsohn and Muren, 1951). From 

 figures given by Stromblad (19560 and b) it appears that this is 

 true for the atrophy also. A continuous secretion due to sponta- 

 neous activity, however, does not prevent the atrophy following 

 section of the chorda in the sublingual gland (Emmelin, 19530). 



Many of the changes characteristic of a denervated gland can 

 be reproduced in a normally innervated gland by long-continued 

 treatment with a parasympatholytic agent like atropine. It is a 

 puzzling fact, however, that no atrophy seems to follow such 

 treatment (Emmelin, Jacobsohn and Muren, 1951 ; Stromblad, 

 19560 and b). This may be connected with the fact that atropine 

 does not entirely abolish the effects of the chorda, since a raised 

 metabolism and vasodilatation can persist. 



Section of the chorda on one side affects the contralateral gland 

 also; it increases somewhat in size (Emmelin, Jacobsohn and 

 Muren, 1951). 



An atrophy has been observed in the parotid gland following 

 destruction of the preganglionic, parasympathetic fibres (Bradford, 

 1888). In the investigation of Stromblad (19550) th e atrophy of 

 the parotid gland after pre- or postganglionic denervation seemed 

 to be relatively small. 



Sympathetic denervation is not followed by atrophy in the sub- 

 maxillary and parotid glands (Bradford, 1888; Stromblad, 1956c). 

 After extirpation of the superior cervical ganglion there may even 

 be a slight increase in the weight of the glands. Whether this is due 

 exclusively or at least to some extent to a greater content of blood 

 following the loss of vasoconstrictor tone has not been investigated. 



The microscopic picture of the submaxillary gland following 

 section of the chorda shows a decrease in size of all structures of the 

 gland except the connective tissue which seems to increase in 



