Alterations in size and structure of submandibular and retrolingual glands of the rat produced by unilateral sectioning of the chorda tympani, or the lingual nerve, or the glandular branch which leaves the lingual and innervates both glands, are described. The glands were studied 1, 2, 4, 8, 12 and 16 days after nerve section.The weight of the glands increased the first day after nerve section and decreased markedly from then on, reaching 40 to 70% of the initial weight after 16 days. In the glands where the chorda tympani or the lingual nerve were sectioned the increase in weight was attributed to the accumulation of secretion in the acinous cells. After that, a progressive atrophy developed, being more severe in the acini than in the tubes.In the cases where the glandular nerve was sectioned a wide necrosis probably of vascular origin was produced, followed by parenchymatous regeneration. In both cases 16 days after nerve section glands were small, fibrous and with little parenchyma.The role of the parasympathetic nerves in controlling the normal structure of submandibulars and retrolinguals is discussed.The chorda tympani has been sectioned in several animals, chiefly in dogs, cats and rabbits. A summary of the results may be found in the monograph of Burgen and Emmelin ('61). These studies indicated a 30% decrease in submandibular gland size, and, microscopically, a variable atrophy of the different structures with relative increase in connective tissue stroma.Rawlinson ('35) studied the changes produced in the submandibular gland of the cat by sectioning the chorda tympani. He described alterations in the epithelium of striated tubules. Clear areas and vacuoles appeared between the striations and the cells gradually decreased in size with pseudostratification of the nuclei.Lacassagne and Causs6 ('41) sectioned the chorda tympani inside the ear in mice and found considerable changes in submandibular and retrolingual glands. There was also atrophy in the retrolingual glands and in the acinous portion of the submandibular. In females the striated tubules of the submandibulars were permanently atrophic, while in males there was only a slight and transient atrophy. This latter ANAT. REC.. 150: 25-34.effect has been attributed to protective action of androgens.Hillarp ('49) sectioned the chorda tympani inside the ears of rats and found moderate atrophy of tubules and acini.Emmelin, Jacobsohn and Muren ('52) sectioned the chorda tympani in cats. The alterations in the striated tubules were similar to those found by Rawlinson; both also found atrophy in the acini and increase in the connective tissue stroma.Several parasympathetic denervations were performed in our laboratories with the object of studying the role of the chorda tympani in the production of submandibular and retrolingual hypertrophy by repeated incisor amputations (Houssay, Peronace, Perec and Rubinstein, '62). The severe atrophy of the denervated submandibulars and retrolinguals was remarkable. The object of this paper is to study serially ...
Dietary administration of proteolytic enzymes such as chymotrypsin, trypsin, bacterial protease, or papain resulted in a marked increase in the weight of the submandibular salivary glands. After sympathectomy, but not parasympathectomy, the response of the glands to papain was partially reduced. After complete autonomic denervation the papain effect was absent completely. The enzymes retained their sialadenotrophic action when administered as intra-oral drops, but were not effective if administered by stomach tube. Although the response to papain was completely absent after section of the glossopharyngeal nerves, section of the lingual nerves did not affect the response. The sialadenotrophic effect of repeated amputation of lower incisor teeth was not altered by prior section of the glossopharyngeal or lingual nerves. The results suggest that the sialadenotrophic action of proteolytic enzymes depends on a neural reflex arc. The afferent arm consists of the taste receptors innervated by the glossopharyngeal nerves, while the efferent arm is composed of both branches of the autonomic nervous supply to the glands.
Within 8 days after a submandibular salivary gland is deprived of its parasympathetic nervous innervation, the gland undergoes a marked reduction in weight. After either sympathectomy or parasympathectomy, the increase in gland weight which usually follows incisor amputation or dietary pancreatin is partially inhibited. The gland weight response to these two stimuli is completely inhibited after combined sympathectomy and parasympathectomy. In contrast, the response of the glands to isoproterenol is not dependent upon nervous innervation since administration of the drug still causes glandular enlargement after partial or complete denervation. Compensatory growth of the remaining submandibular gland after removal of one gland and ligation of the ducts of the parotid glands is partially inhibited by section of either nervous branch alone and almost entirely inhibited after complete denervation. A small but definite compensatory response still occurs after complete denervation indicating that humoral as well as nervous factors may be involved in this response. In hypophysectomized rats the response of the submandibular glands to growth hormone administration is not impaired by partial or complete autonomic denervation, indicating that nervous factors do not have a role in this effect of growth hormone.
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