Secretory and Structural Changes in the Parotid Salivary Gland of Sheep and Lambs After Parasympathetic Denervation

Abstract

The effect of the parasympathetic nerve supply on the development of the parotid gland in the immature lamb and its maintenance in the adult sheep has been investigated by unilateral postganglionic denervation. Seventy-seven to ninety-three days after denervation secretory activity of the gland was examined and material taken for histological examination. The adult denervated glands secreted at lower rates than the innervated and their atropine-resistant secretory flow was reduced to as low as one fifth of that of the innervated glands. In two lambs an atropine-resistant flow did not develop in the denervated glands: in another two, flows of saliva from the denervated glands were present but were much less than in the contralateral innervated glands. After denervation glands were, with one exception, smaller than the contralateral innervated glands. The acinar cells of the denervated adult and lamb glands were smaller than the cells of the innervated glands but similar in size to those of 7-14 day old unoperated control lambs. Acinar cells in denervated glands had periodic acid Schiff staining material but the staining reaction to pyronin-methyl green was similar in the innervated and denervated. The results indicate that the integrity of the parasympathetic innervation is essential for the development of the parotid gland of the sheep and for its maintenance in the adult animal.The adult ruminant parotid salivary gland has a profuse serous secretion of similar osmolality to plasma. The voluminous output [Kay, 1960a] includes a spontaneous secretion which persists after denervation of the glands, or the administration of autonomic blocking agents and has been demonstrated in the excised perfused gland. Evidence on these features of the activity of the glands and on the contribution their secretions make to the maintenance of stable conditions in the more cranial parts of the stomach where fermentative digestion of plant material occurs, has been reviewed by Kay [1966].The parotid salivary gland of the new-born ruminant is histologically immature and has little secretory activity [Kay, 1960b] until the ingestion of solid food commences. Its development has been associated with the ingestion of solid material [Wilson, 1963]. The more cranial divisions of the stomach are also immature in the newly born ruminant and their more complete development occurs as fermentative digestion due to micro-organisms becomes established. Chemical and mechanical stimuli that have been shown to exert direct effects on the stomach [Brownlee, 1956;Harrison, Warner, Sander and Loosli, 1960;Warner and Flatt, 1965] have a special role in this.We sought in the present experiments to determine the effects of the parasympathetic innervation on the development of the secretion and structure of the parotid salivary glands of the lamb and on the maintenance of the secretion and structure in the adult. 223 IC ) .L I ILJA ,

Salivary glands regenerate after radiation injury through SOX2‐mediated secretory cell replacement

“…Similar to the effect of radiation therapy on tissue structure (Sullivan et al , ; Redman, ) adult acinar cells, as well as SOX2 + progenitors, were more sensitive to the loss of innervation than ducts. Denervation resulted in reduced acinar cell size (as observed previously; Patterson et al , ; Fig EV3B) decreased AQP5 protein and transcript levels of the differentiated acinar cell marker Muc19 (Fig B and D). Interestingly, transcript and protein levels of MIST1 were unchanged following denervation (Fig B, E and F), suggesting that while functional markers of acinar cells are disrupted in the absence of innervation, acinar cell identity is not adversely affected.…”

A Salivation Abnormality with Trigeminal Nerve Dysfunction in Dogs

“…13 Experimentally, injury to the nerve supplying parasympathetic innervation to the parotid gland results in atrophy of the gland. 29 Specifically, experimental injury at the level of the oval foramen that involves the otic ganglion results in parotid gland atrophy, whereas partial injury of the otic ganglion, which spares some parasympathetic innervation, may not result in atrophy of the parotid gland. 20,23 Significant differences in the largest cross-sectional area measurements were observed on the MRI studies in a cohort of dogs in this report.…”

“…Fatty infiltration secondary to denervation occurs with denervation of the salivary glands. 29 An increase in fat composition would be expected to increase the mean signal intensity on a T2W image. Despite this, subjective differences in the microscopic evaluation of the salivary glands were not noted.…”