THE NERVES OF THE SALIVARY GLANDS, 285 



readily stain with carmine, whilst their nucleus is scarcely, if at all, 

 coloured by the dye. The researches of R. Heidenhain (1868) have 

 shed much light on the secretory activity of the salivary glands. 



The change may be produced in two ways. Either it is due to the "mucous cells " 

 during secretion becoming broken up, so that they yield their mucin directly to the 

 saliva ; in saliva rich in mucin, small microscopic pieces of mucin are found, and 

 sometimes mucous cells themselves are present. Or, we must assume that the 

 mucous cells simply eliminate the mucin from their bodies (Ewald, Stohr); while, 

 after a period of rest, new mucin is formed. According to this view, the dark 

 granular cells of the glands, after active secretion, are simply mucous cells, which 

 have given out their mucin. If we assume, with Heidenhain, that the mucous 

 cells break up, then these granular non-mucous cells must be regarded as new 

 formations produced by the proliferation and growth of the composite marginal cells, 

 i.e., the crescents, or half -moons of Gianuzzi. 



[During rest, the protoplasm seems to manufacture mucigen, which is 

 changed into and discharged as mucin in the secretion, when the gland 

 is actively secreting. Thus, the cells become smaller, but the proto- 

 plasm of the cell seems to increase, new mucigen is manufactured during 

 rest, and the cycle is repeated.] 



144. The Nerves of the Salivary Glands. 



The nerves are for the most part medullated, and enter at the hiluni 

 of the gland, where they form a rich plexus provided with ganglia 

 between the lobules. [According to Klein, there are no ganglia in the 

 parotid gland.] 



All the salivary glands are supplied by branches from two different 

 nerves from the sympathetic and from a cranial nerve. 



1. The sympathetic nerve gives branches to (a.) the sub-maxillaiy 

 and the sub- lingual glands, derived from the plexus on the external 

 maxillary artery (6.) to the parotid gland from the carotid plexus. 



2. The facial nerve gives branches to the sub-maxillary and 

 sub-lingual glands from the chorda tympani which accompanies the 

 lingual branch of the fifth nerve. The branches to the parotid 

 reach it in a roundabout way. They arise from the tympanic branch 

 of the glosso-pharyngeal nerve (dog). The tympanic plexus sends 

 fibres to the small superficial petrosal nerve (Eckhard, Loeb, Heiden- 

 hain), and with it these fibres run to the anterior surface of the 

 pyramid in the temporal bone, and, after passing through the fora- 

 men lacerum anticum, reach the otic ganglion. This ganglion sends 

 branches to the auriculo-temporal nerve (itself derived from the third 

 branch of the trigeminus), which, as it passes upwards to the tem- 

 poral region under cover of the parotid, gives branches to this gland 

 (v. Wittich). 



The sub-maxillary ganglion, which gives branches to the sub- 



