94 HUMAN PHYSIOLOGY 



lying at the periphery of the gland wall. They are flattened 

 cells with protoplasm rich in granules. 



2. Muciparous cells, reaching to the lumen of the gland 

 duct ; their protoplasm is but slightly granular, more hyaline. 



These two forms of cells are of the same kind, but are in 

 different conditions of secretion. The well-filled muciparous 

 cells, a^ , a 2 , a 3 (Fig. 3, I) crowd the empty border cells 

 b l , b 2 , b^, away from the lumen. After discharging their 

 secretion, the hitherto muciparous cells are crowded away 

 by the now filled border cells and are themselves changed 

 to border cells (compare the change in the form of the cells 

 in the successive stages II, III, IV of Fig. 3). 



3. Influence of the nervous system upon secretion. The 

 salivary secretion is stimulated reflexly when food, especially 

 dry food, stimulates the nerves of the mucous membrane of 

 the mouth. Salivary secretion is, therefore, dependent upon 

 the nervous system. 



The submaxillary and sublingual glands are supplied 

 with the following secretory nerves : 



(a] Fibres from the facial nerve which, passing through 

 the chorda tympani, approach the glands along with the 

 lingual. Stimulation of these fibres produces a rich flow of 

 thin secretion. 



(b) Fibres from the cervical sympathetic; the stimulation 

 of these yields a scanty flow of thick saliva. 



The chorda fibres also contain the vaso-dilators ; the 

 sympathetic contain the vaso-constrictors for the blood 

 vessels of the glands. 



The parotid glands are supplied with the following secre- 

 tory fibres : 



(a) Fibres from the glossopharyngeal passing through the 

 nervus Jacobsonii, Petrosus superficialis minor to the oticum 

 ganglion, from there through the auriculo temporalis to the 

 gland. Stimulation of these produces a great flow of thin 

 saliva. 



(b) Fibres of the cervical sympathetic, stimulation of which 

 yields a scanty flow of thick secretion. 



