Primary Centres of Salivary Secretion 239 



central nervous system in curarized dogs and studied the effect on 

 the submaxillary secretion evoked reflexly by afferent stimulation. 

 The reflex was retained as long as the section was made rostrally 

 to the region containing the nucleus of the facial nerve. 



Histological methods were applied by Kohnstamm (1902, 1907), 

 Solomowicz (1908), and Yagita and Hayama (1909, 19 10). After 

 degenerative section of the preganglionic parasympathetic fibres in 

 dogs, the chromatolysis in the brain stem was studied. As a result 

 of this work it was established that a "nucleus salivatorius" consist- 

 ing of a neurone pool in the reticular formation extends from the 

 nucleus of the facial nerve to the anterior part of the nucleus 

 ambiguus. The rostral portion, the nucleus salivatorius superior, 

 is connected with the submaxillary and presumably the sublingual 

 gland, the nucleus salivatorius inferior with the parotid gland. 

 Clinical observations suggest that a similar arrangement exists in 

 man (Feiling, 19 13). 



Stimulation experiments, combined with histological examina- 

 tion, have confirmed these findings. Miller (191 3) stimulated elec- 

 trically the dorsal surface of the medulla oblongata in decerebrate 

 cats using a unipolar electrode. When currents of minimal intensity 

 were used it was possible to localize one point yielding only parotid, 

 and a second point yielding only submaxillary secretion; responses 

 were obtained solely from the ipsilateral glands. The "parotid 

 point" was situated about 6 mm in front of the tip of the calamus 

 scriptorius, the "submaxillary point" about 2 mm in front of the 

 "parotid point". More recently the salivary centres have been ex- 

 plored systematically (Fig. 12.1) using small, bipolar electrodes in 

 cats (Chatfield, 1941 ; Wang, 1943) and monkeys (Magoun and 

 Beaton, 1942). From this work it is obvious that there is no sharp 

 division between the two salivary nuclei ; in the intermediate zone, 

 stimulation yields both submaxillary and parotid secretion. It may 

 be of interest to point out in this connection that the human parotid 

 gland is supposed to be supplied not only by glossopharyngeal, but 

 also by facial fibres (Reichert and Poth, 1933). In the stimulation 

 experiments of the more recent investigators a parasympathetic 

 mechanism was activated, for the secretory responses were abol- 

 ished by atropine or parasympathetic denervation. In an investi- 

 gation on "pseudomotor contracture" in the tongue, Corbin, 

 Harrison and Wigginton (1941) found that stimulation of the 

 intramedullary portion of the seventh nerve and the reticular matter 



