• Applied Microscopy
• /
• v.47 no.1
• /
• pp.8-12
• /
• 2017

The ultrastructures of the secretory acinar granules of submandibular and parotid salivary gland were examined in the Korean striped field mouse, Apodemus agraius. The acini of the submandibular salivary gland had serous and mucous acinar cells filled with numerous secretory granules. The serous acinar granules had uniformly fine dense contents and were round typed with a definite boundary between the granules. The mucous acinar granules were relatively coarse, with moderate density, and clustered together as a result of the indistinct boundaries between the granules. The acini of the parotid salivary glands contained only serous cells filled with numerous round-typed serous acinar granules. Serous acinar granules had uniformed dense matrix and definite boundaries. The ultrastructures without substructure in a matrix of serous and mucous acinar granules in the submandibular and parotid salivary glands of A. agraius were similar to those of species of Rodentia but different from those of Soricidae in Korea with a characteristic substructure in a matrix. This ultrastructure and charateristics in secretory acinar granules provide fundamental data for molecular comparisions of genetic relationships and are one of the key methods for classifying A. agraius.

• International Journal of Oral Biology
• /
• v.45 no.2
• /
• pp.58-63
• /
• 2020

The salivary glands secrete saliva, which plays a role in the maintenance of a healthy oral environment. Under physiological conditions, saliva secretion within the acinar cells of the gland is regulated by stimulation of specific calcium (Ca²⁺) signaling mechanisms such as increases in the intracellular Ca²⁺ concentration ([Ca²⁺]_i) via storeoperated Ca²⁺ entry, which involves components such as Orai1, transient receptor potential (TRP) canonical 1, stromal interaction molecules, and inositol 1,4,5-triphosphate (IP₃) receptors (IP₃Rs). Homer proteins are scaffold proteins that bind to G protein-coupled receptors, IP₃Rs, ryanodine receptors, and TRP channels. However, their exact role in Ca²⁺ signaling in the salivary glands remains unknown. In the present study, we investigated the role of Homer2 in Ca²⁺ signaling and saliva secretion in parotid gland acinar cells under physiological conditions. Deletion of Homer2 (Homer2^-/-) markedly decreased the amplitude of [Ca²⁺]_i oscillations via the stimulation of carbachol, which is physiologically concentrated in parotid acinar cells, whereas the frequency of [Ca²⁺]_i oscillations showed no difference between wild-type and Homer2^-/- mice. Homer2^-/- mice also showed a significant decrease in amylase release by carbachol in the parotid gland in a dose-dependent manner. These results suggest that Homer2 plays a critical role in maintaining [Ca²⁺]_i concentration and secretion of saliva in mouse parotid gland acinar cells.

• Applied Microscopy
• /
• v.24 no.1
• /
• pp.28-40
• /
• 1994

Xerostomia and xerophthalmia are delicate or serous side effects, occuring when the radiotherapy is administered to the head and neck cancer patient. It is known that the cause of the above side effect is radiosensitivity of serous cells. In this study, the ultrastructural features of the parotid glands of the X-irradiated rats were observed. Sprague-Dawley rats weighing 200-250g each were anesthetized with sodium thiopental, and placed on the Mitsubishi linear accelerator. Only the head and neck areas of animals were exposured at the distance of 80cm, within the area of $30X30cm$, in the depth of 1cm, with the speed of 200R/min. Total doses applied were 3,000R or 6,000R depending on the experimental groups. Animals were sacrificed on the 6th hour, 2nd day and 6th day after the irradiation. Parotid glands were fixed in the 2.5% glutaraldehyde-1.5% paraformaldehyde solution, and followed by refixation in the 1% osmium tetroxide solution. Dehydrated blocks were embedded in araldite mixture, and ultrathin sections were cut. Sections were contrasted with the solution of uranyl acetate and lead citrate, and observed with JEM 100 CX-II electron microscope. The results were as follows: 1. Normal parotid acinar cells are two types; the light and the dark acinar cells. The light acinar cell contains dense secretory granules, whereas dark acinar cells contains granules of medium density with some darker spots within them, or other cells contain granules of medium density with darker rims. 2. Six hours after the irradiation, many acinar cells were degenerated showing variable stages of cytolytic bodies, light bodies, or dense degenerations. Within the acinar cell, Golgi apparatus and granular endoplasmic reticula were most severely altered elements. Granules showed more contrasting densities and irregularities. 3. Two days after the irradiation, some cytolytic bodies, and focal lucent degeneration of cytoplasm, and fine granular alteration of cytoplasmic matrix were pronounced. But other elements including secretory granules are rather looked unlatered. 4. Six days after the irradiation, most severe alterations were seen. Many intracellular canaliculi (or secretion figures), quanta of cytoplasm containing secretion antecedants, severely irregular luminal border, and again contrasting density of secretory granules showing tigroid spots or dense rims were noted. And myoepithelial degenerations were observed not uncommonly. 5. Irregular densities of secretory granules were interpreted as abnormal components of protein or carbohydrate portion are synthesized or abnormally metabolized under severe X-irradiation. 6. Myoepithelial degeneration and related alteration of nerve endings, etc., were suggested as the other causes of xerostomia following X-irradiation. 7. It is requested that radiation doses should be arranged, considering in mind not only the sensitivity of acinar cells but also the myoepithelial and neural functions.

• Korean Journal of Veterinary Research
• /
• v.34 no.4
• /
• pp.715-725
• /
• 1994

The ultrastructural investigations of the parotid gland of Korean native goat were carried out by transmission electron microscopy. The results were as follows; 1. The acini of parotid gland were composed of light and dark acinar cells. 2. In the light acinar cells, the secretory granules were classified into three types according to their electron densities and dense bodies. One type of granules was low electron density and had no dense bodies. Another type was low electron density and had dense bodies, and the other type was low electron density and had granular dense bodies. 3. The secretory granules of dark acinar cells showed high electron density and were also calssified into three types by dense bodies as the same way as in the light acinar cells. 4. The intercalated ducts consisted of simple cuboidal epithelium. The nuclei of epithelial cells were oval or round form, located at the central part, and had infolding nuclear membranes and one or two nucleoli. 5. The cells of both of the striated and excretory ducts were composed of light cells, dark cells, specific light cells and basal cells. 6. The nerve terminals were distinguished into two types. One had large granular synaptic vesicles, and another had small agranular synaptic vesicles.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.18 no.1
• /
• pp.31-45
• /
• 1988

The author studied the histopathologic changes according to a single or a split dose and the time after irradiation on the acinar cells of rat parotid gland. 99 Sprague Dawley rats, weighing about l20gm, were divided into control and 3 experimental groups. In experimental groups, GroupⅠ and Ⅱ were delivered a single dose of l5Gy, 18Gy and Group Ⅲ and Ⅳ were delivered two equal split doses of 9Gy, 10.5Gy for a 4 hours interval, respectively. The experimental groups were delivered by a cobalt-60 teletherapy unit with a dose rate of 222cGy/min, source-skin distance of 50㎝, depth of l㎝ and a field size of l2×5㎝. The animals were sacrificed at 1, 2, 3, 6, 12 hours, 1, 3, 7 days after irradiation and examined by light and electron microscopy. The results were as follows: 1. As the radiation dose increased and the acinar cells delivered a single dose exposure were more damaged, and the change of acinar cells appeared faster than those of a split dose exposure. 2. The histopathologic change of acinar cells appeared at 1 hour after irradiation. The recovery from damaged acinar cells appeared at 1 day after irradiation and there was a tendency that the recovery from damage of a split dose exposure was somewhat later than that of a single dose exposure. 3. Light microscope showed atrophic change of acinar cells and nucleus, degeneration and vesicle formation of cytoplasm, widening of intercellular space and interlobular space. 4. Electron microscope showed loss of nuclear membrane, degeneration of nucleus and nucleoli, clumping of cytoplasm, widening and degeneration of rough endoplasmic reticulum, loss of cristae of mitochondria, lysosome, autophagosome and lipid droplet. 5. Electron microscopically, the change of rough endoplasmic reticulum was the most prominent and this appeared at 1 hour after irradiation as early changes of acinar cells. The nuclear change appeared at 2 hours after irradiation and the loss of cristae of mitochondria was observed at 2 hours after irradiation in all experimental groups.

• The Korean Journal of Physiology and Pharmacology
• /
• v.22 no.2
• /
• pp.215-223
• /
• 2018

Intracellular $Ca^{2+}$ mobilization is closely linked with the initiation of salivary secretion in parotid acinar cells. Reactive oxygen species (ROS) are known to be related to a variety of oxidative stress-induced cellular disorders and believed to be involved in salivary impairments. In this study, we investigated the underlying mechanism of hydrogen peroxide ($H_2O_2$) on cytosolic $Ca^{2+}$ accumulation in mouse parotid acinar cells. Intracellular $Ca^{2+}$ levels were slowly elevated when $1mM\;H_2O_2$ was perfused in the presence of normal extracellular $Ca^{2+}$. In a $Ca^{2+}-free$ medium, $1mM\;H_2O_2$ still enhanced the intracellular $Ca^{2+}$ level. $Ca^{2+}$ entry tested using manganese quenching technique was not affected by perfusion of $1mM\;H_2O_2$. On the other hand, $10mM\;H_2O_2$ induced more rapid $Ca^{2+}$ accumulation and facilitated $Ca^{2+}$ entry from extracellular fluid. $Ca^{2+}$ refill into intracellular $Ca^{2+}$ store and inositol 1,4,5-trisphosphate ($1{\mu}M$)-induced $Ca^{2+}$ release from $Ca^{2+}$ store was not affected by $1mM\;H_2O_2$ in permeabilized cells. $Ca^{2+}$ efflux through plasma membrane $Ca^{2+}-ATPase$ (PMCA) was markedly blocked by $1mM\;H_2O_2$ in thapsigargin-treated intact acinar cells. Antioxidants, either catalase or dithiothreitol, completely protected $H_2O_2-induced$ $Ca^{2+}$ accumulation through PMCA inactivation. From the above results, we suggest that excessive production of $H_2O_2$ under pathological conditions may lead to cytosolic $Ca^{2+}$ accumulation and that the primary mechanism of $H_2O_2-induced$ $Ca^{2+}$ accumulation is likely to inhibit $Ca^{2+}$ efflux through PMCA rather than mobilize $Ca^{2+}$ ions from extracellular medium or intracellular stores in mouse parotid acinar cells.

• Applied Microscopy
• /
• v.35 no.4
• /
• pp.91-97
• /
• 2005

The acinar cells and secretory granules of the parotid salivary gland were examined in the lesser white toothed shrew, Crocidura suaveolens and the big white-toothed shrew, C. lasiura. The parotid gland of both species were a serous gland having only one kind of serous acinar cells, and had conventional arrangement of acini and intercalated, granular and striated ducts. In case of C. suaveolens, serous acinar cells had well developed rER, prominent Golgi complex, several large mitochondria and abundant moderate dense secretory granules with various stages of the maturing or fusing process. Immature acinar secretory granules were only or mainly filled with fine strong dense specks and had an indistinct limiting membrane, and mature granules were filled with homogeneous pale large round center and had fine strong dense specks at the periphery of the homogeneous pale center and a distinct limiting membrane. In case of C. lasiula, serous acinar cells had well developed rER, prominent Golgi complex, several large mitochondria and abundant dense secretory granules with maturing or fusing process. Immature acinar secretory granules were only filled with pale rough specks and had an indistinct limiting membrane, and mature granules were only filled with rough dense specks and had a distinct limiting membrane. Eventually The acinar secretory granules of C. suaveolens were seen moderate at the light and ultrastuctural level, those of C. lasiura were strong dense at the light microscopic level and dense at the ultrastructural level.

• Journal of Oral Medicine and Pain
• /
• v.24 no.2
• /
• pp.163-169
• /
• 1999

We investigated the culture condition and effects of various growth factors on the culture of salivary gland acinar cells. Male, Sprague-Dawley rats (about 6 weeks old) were sacrificed and their submandibular, sublingual, and parotid glands were used as specimens. High oxygen level more than 90% and coating of Matrigel on culture dish were important factors to help increase the survival time of acinar cells, Proper concentration of enzymes such as collagenase and hyaluronidase during isolation steps was also important. Addition of various growth factors such as dexamethasone, insulin, transferrin, selenous acid, reduced glutathione, epidermal growth factor, isoproterenol, and putrescine in culture medium helped to increase lifetime of cultured salivary acinar cells.

• Journal of dental hygiene science
• /
• v.22 no.2
• /
• pp.83-89
• /
• 2022

Background: Estrogen deficiency affects the structure and function of the salivary glands in women, leading to a decrease in salivary secretion and a change in the composition of saliva. Previous studies on changes in the salivary glands that cause estrogen deficiency have reported only partial results for the parotid and submandibular glands, and there are few comparative morphological studies of histological changes between the parotid and submandibular glands in ovariectomized rats (OVX) leading to estrogen deficiency. This study aimed to analyze the histopathological and histochemical changes in the parotid and submandibular salivary glands causing estrogen deficiency by using OVX, and to discuss the mechanism on these changes. Methods: The parotid and submandibular glands from sacrificed control and OVX groups were fixed with cold 4% paraformaldehyde in phosphate buffer (pH 7.2). The tissues were dehydrated using a series of graded ethyl alcohol and embedded in paraffin. For histopathological analysis, sections cut to a thickness of 6 to 7 ㎛ were stained with hematoxylin and eosin (H&E). For histochemical analysis, Periodic acid-Schiff (PAS), Alcian blue (AB, pH 2.5), and PAS+AB (pH 2.5 and pH 1) staining was performed. Results: Histopathological analysis of OVX tissue showed that the parotid and submandibular salivary glands were broadly and clearly separated and divided into lobes. In OVX, acinar and ductal cells with condensed polymorphic or pyknotic nucleus, which are presumed to be characteristic of apoptotic cells, and degenerated cells with lipid deposition in cytoplasmic granules and ruptured membranes were increased. Histochemical analysis of OVX, confirmed an increase in the number and acidification of acinar secretory granules. Conclusion: Histopathological and histochemical changes and the effects of estrogen deficiency are more evident in the submandibular salivary gland than in the parotid gland.

• International Journal of Oral Biology
• /
• v.33 no.4
• /
• pp.143-147
• /
• 2008

The sodium bicarbonate cotransporter (NBC) protein is functionally expressed in salivary glands. In this experiment, we examined the role of NBC in $HCO_3^-$ formation in human parotid gland acinar cells. Intracellular pH (pHi) was measured in 2'-7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF)-loaded cells. Acetazolamide (0.1 mM) and 4,4'-diisothio cyanatostilbene-2,2'-disulphonic acid (DIDS, 0.5 mM) were used as specific inhibitors of carbonic anhydrase and NBC, respectively. The degree of inhibition was assessed by measuring the pHi recovery rate (${\Delta}pHi$/min) after cell acidification using an ammonium prepulse technique. In control experiments, ${\Delta}pHi$/min was $1.40{\pm}0.06$. Treatment of cells with 0.5 mM DIDS or 0.1 mM acetazolamide significantly reduced ${\Delta}pHi$/min to $1.14{\pm}0.14$ and $0.74{\pm}0.15$, respectively. Simultaneous application of DIDS and acetazolamide further reduced ${\Delta}pHi$/min to $0.47{\pm}0.10$. Therefore, DIDS and acetazolamide reduced ${\Delta}pHi$/min by 19% and 47%, respectively, while simultaneous application of both DIDS and acetazolamide caused a reduction in ${\Delta}pHi$/min of 67%. These results suggest that in addition to carbonic anhydrase, NBC also partially contributes to $HCO_3^-$ formation in human parotid gland acinar cells.