PAROTID GLAND 241 



Vessels and Nerves. The arteries generally follow the ducts from the 

 connective tissue septa into the lobules, where they produce abundant 

 capillary networks close to the basement membranes. The veins derived 

 from these soon enter the interlobular tissue, and may then accompany 

 the arteries. The lymphatic vessels follow the ducts, and branch in the 

 interlobular connective tissue, in which they terminate. Only tissue spaces 

 have been found within the lobules. The nerve supply is from several 

 sources. Sympathetic nerves from the plexus around the carotid artery 

 accompany the blood vessels into the parotid gland, and by controlling 

 the blood supply have an important bearing upon secretion. The nerves 

 which reach the gland cells are in connection with the tympanic branch 

 of the glossopharyngeal nerve. This branch extends to the otic ganglion, 

 from which fibers pass to the parotid gland by way of an anastomosis 

 with the auriculo-temporal branch of the mandibular nerve. Within the 

 gland the nerves pass along the ducts, where they are associated with 

 microscopic ganglia, and form plexuses beneath the basement membranes 

 of the alveoli. From these plexuses, fibers penetrate the basement mem- 

 branes and form simple or branched varicose endings in contact with the 

 gland cells. Other nerves enter the substance of the gland, either to pass 

 through it or to contribute to its nerve supply; these include branches 

 of the trigeminal, facial and great auricular nerves, the last coming from 

 the second and third cervical nerves. Free sensory endings of medullated 

 fibers are said to occur in the epithelium of the ducts. 



Mucous Glands. 



The purely mucous glands of the mouth are simple branched alveolo- 

 tubular glands found on the anterior surface of the soft palate and on the 

 hard palate (palatine glands), along the borders of the tongue (lingual 

 glands'), and in greater numbers in the root of the tongue. There they 

 may open into the tonsillar pits through ducts lined with columnar epi- 

 thelium, sometimes ciliated. The wall of the tubules consists of a struc- 

 tureless basement membrane and of columnar mucous cells j varying ac- 

 cording to their functional condition as shown in Fig. 227, I-II. The 

 empty cells are narrower than the others, and the nuclei, though at 

 the base of the cell and transversely oval, are not as flat as in cells 

 full of secretion. Seldom can cells be found completely occupied by 

 unaltered protoplasm. A single gland, or even a single alveolus, may 

 contain cells in different phases of secretion, as is clearly seen when special 

 mucin stains are used. Secretory capillaries are not found in the purely 

 mucous glands. 



Mixed Glands. 



The mixed oral glands are the sublingual, submaxillary, anterior lin- 

 gual, labial, buccal, and molar glands. They all possess crescents of 



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