Rat cytomegalovirus replication in the salivary glands is exclusively confined to striated duct cells

The salivary gland is the preferred organ for cytomegalovirus (CMV) replication and viral persistence. In order to identify the nature of infected cells and to study viral replication in more detail, several experiments were conducted. Using the rat CMV (RCMV) model, acutely infected young adult rats (6 weeks of age) and new-born rats (3 days of age) were infected, and submandibular, parotid and sublingual glands were harvested at different time points after infection. For identification of the nature of infected cells, immunohistochemistry, in situ hybridisation and electron microscopic techniques were used. In young adult animals, the submandibular gland was the preferred organ for RCMV replication. The parotid and sublingual glands contained fewer viruses than the submandibular gland. In contrast, in new-born rats, the main site of RCMV replication was the sublingual gland, while the submandibular and parotid glands contained low amounts of virus. No virus could be detected in the parotid glands. In all glands of RCMV-infected animals, the infection was exclusively confined to striated duct cells. Infection resulted in a cellular inflammatory response which was mostly located in the interlobular duct region, whereas only few inflammatory cells were found in the neighbourhood of infected striated duct cells. This phenomenon may contribute to the long persistence of the virus in this organ. Received: 25 May 2000 / Accepted: 26 May 2000     

Sarcomatoid salivary duct carcinoma of the parotid gland

Salivary duct carcinoma (SDC) is a high-grade neoplasm known to histologically resemble high-grade ductal carcinoma in situ of the breast. We describe 3 cases of sarcomatoid salivary duct carcinoma, a heretofore unreported variant of SDC. Each case was a composite of SDC and sarcomatoid carcinoma and histologically similar to reported cases arising in the breast. The clinicopathologic features, including immunohistochemistry, of 3 cases were investigated. In the 3 men, ages 56, 68, and 70 years, the resected parotid tumors measured 1.5, 3.5, and 1.5 cm, respectively. Only the 3.5-cm tumor extended beyond the parotid gland into soft tissue. This patient died at 3 years with pulmonary metastases. The other patients were free of disease at 6 and 12 months. Histologically, each case was a composite of usual-type SDC and sarcomatoid carcinoma. SDC showed typical cribriform architecture, whereas anaplastic, spindled cells constituted the sarcomatoid areas. Immunohistochemically, epithelial elements stained as follows: cytokeratin (AE1/AE3 & CAM 5.2) positive in 3 of 3 cases, EMA positive in 3 of 3 cases, vimentin negative in 3 of 3 cases, desmin negative in 3 of 3 cases, c-erbB-2 positive in 1 of 2 cases. Sarcomatoid elements stained as follows: AE1/AE3 negative in 3 of 3 cases, CAM 5.2 rare positive cell in 1 of 3 cases, EMA focally positive in 3 of 3 cases, vimentin positive in 3 of 3 cases, desmin negative in 3 of 3 cases, c-erbB-2 negative in 2 of 2 cases. Electron microscopy, performed in one case, showed scattered junctional complexes congruent with epithelial differentiation. Immunohistochemical results, EMA and CAM 5.2 positivity, and ultrastructural findings supported our belief that these unique biphasic tumors represented SDC with sarcomatoid carcinoma. We conclude an element of sarcomatoid carcinoma rarely may arise in association with SDC, and it is erroneous to diagnose such tumors as "carcinosarcoma."     

Crystalloids in salivary duct cysts of the human parotid gland

Summary Crystalloids found in salivary duct cysts of the human parotid gland were examined by scanning electron microscopical observations with electron probe X-ray microanalysis. The cystic spaces were filled with numerous crystalloids which had a variety of forms with slight eosinophilic and glassy appearance. Scanning electron microscopically, crystalloids were hexagonal and rhombohedral in shape, and cutting the surface showed a polycyclic structure or regular parallel lamination. By electron probe X-ray microanalysis, sulphur was the only detected element. The present study suggests that crystalloids resulted from deposition from supersaturated saliva containing sulphur containing compounds into the cystic lumen or into epithelial cytoplasm.     

Characterization of cytoskeletal proteins in basal cells of human parotid salivary gland ducts

Summary From previous immunofluorescent, immunohistochemical and ultrastructural studies, myoepithelial cells have been reported to be absent from the striated and excretory ducts of human salivary gland. Yet recently, certain anti-cytokeratin monoclonal antibodies which specifically label the myoepithelium of salivary gland acini and intercalated ducts have also been found to stain basally situated cells in both striated and excretory ducts. In this study, we have used eight samples of normal human parotid gland (methacarn-fixed and frozen sections) to establish if basal cells of striated and excretory ducts have the cytoskeletal protein complement (actin and cytokeratins) of myoepithelial cells. Using a muscle-specific actin, HHF35, not only is the myoepithelium of acini and intercalated ducts stained in all cases, but stellate and spindle shaped cells are also detected all along the inter- and intralobular striated ducts in four of the eight examples. With double-labeled frozen sections and fluorescent microscopy, the actin-specific probe, phalloidin, and the myoepithelial-selective anti-cytokeratin 14 antibody, 312C8-1, confirm that the striated duct does have a population of basal cells with the cytoskeletal protein make-up of myoepithelium. The monoclonal antibody 8.12 (specific for cytokeratin 13 and 16) also stains some basal cells of striated and excretory ducts, as well as luminal cells of ducts at all levels, but does not label the myoepithelium of acini and intercalated ducts. Both the anti-cytokeratin antibodies and the actin-detecting mechanisms reveal that the basal cell population of striated and excretory ducts is more heterogeneous, and likely functionally more complex, than has been realized previously. Such findings are not in agreement with certain aspects of current theories of the histogenesis of salivary gland tumours.The authors appreciate the funding provided by the Moe Levin Family Foundation, Montreal, Canada     

Aggressive invasive micropapillary salivary duct carcinoma of the parotid gland

The presence of invasive micropapillary component has been reported to be associated with salivary duct carcinoma and poor outcomes. Herein is described a rare case of invasive micropapillary salivary duct carcinoma of the parotid gland in a 60-year-old man. The micropapillary component was approximately 70% of the area of the tumor. Squamous differentiation was focally seen adjacent to the micropapillary component. On immunohistochemistry the ordinary salivary duct carcinoma component was positive for gross cystic disease fluid protein-15 (GCDFP-15), androgen receptor (AR), and HER2/neu, whereas both micropapillary and squamous components were negative for GCDFP-15 and AR. Immunohistochemical staining for D2-40 highlighted the lymph vessel invasion of tumor cells. This patient developed metastases in the lymph nodes of the neck, and also in the liver, lung, and brain. The lymph nodes and liver metastases had both ordinary salivary duct carcinoma and micropapillary components. The patient died of tumor 11 months after the initial surgical operation. The results support that the presence of micropapillary component is associated with more aggressive behavior of salivary duct carcinoma. It is also important for pathologists to recognize that GCDFP-15 and AR expression can be reduced in micropapillary carcinoma in the differential diagnosis of metastatic tumor.     

Ultrastructure of the parotid duct. Cytochemical studies of the striated duct and papillary cystadenoma lymphomatosum of the human parotid gland.

To our knowledge, there are currently no reports in the literature that discuss the fine structure of the striated ducts of the human parotid gland. Papillary cystadenoma lymphomatosum (Warthin's tumor) is a benigh neoplasm found almost exclusively in the parotid gland that represents about 16% of all neoplasms of the gland. This neoplasm is believed to arise from the striated and/or excretory ducts, but there are contradictions with regard to the proposed origin and the cellular composition of some Warthin's tumors. Tissue was obtained at the time of surgery and examined ultrastructurally and cytochemically for the localization of alkaline phosphatase and adenosine triphosphatase. Myoepithelial cells were found ultrastructurally and cytochemically on the proximal aspect of the striated duct, with their cell bodies situated at the junction of the striated and intercalated ducts. Two Warthin's tumors were observed with cells that were structurally and cytochemically similar to myoepithelial cells.     

Synthesis of secretory and plasma membrane glycoproteins by striated duct cells of rat salivary glands as visualized by radioautography after 3H-fucose injection

The ability of the striated ducts of rat salivary glands to incorporate 3H-fucose into glycoprotein was studied by light and electron microscope radioautography. At 3.5 to 20 minutes after intravenous injection, the majority of the radioautographic grains in the ducts of the parotid gland were localized to the Golgi apparatus. By 40 minutes, the percentage of grains over the Golgi apparatus had decreased; a corresponding increase in grains occurred over small (0.1-0.4 micrometer) apical granules and the highly infolded basal and lateral plasma membranes. By two hours, less than 10% of the label was associated with the Golgi apparatus, while 26% and 28% were attributed to the apical granules and plasma membrane, respectively. By 8 to 12 hours after injection, the number of grains over the apical cytoplasm had decreased, suggesint luminal discharge of the apical granules. In contrast, the basal and lateral plasma membranes remained labeled up to 30 hours after injection as judged by the distribution of grains in light microscope radioautographs. Mitochondria appeared capable of independent incorporation of fucose, accounting for about 20% of the grains from ten minutes to two hours after injection. Comparable results were obtained in the striated ducts of the submandibular and sublingual glands. These results indicate that the striated duct cells readily incorporate 3H-fucose into newly-synthesized glycoproteins. A portion of these are secretory glycoproteins which are packaged and stored in the apical granules, and a portion are membrane glycoproteins which are incorporated into the extensive plasma membrane of these cells.     

The structure of the regenerating parotid salivary gland in rats

Summary The number of terminal portions and of their nuclei in 100 fields of view were counted in normal and in regenerating parotid glands. There was no difference either in the number of terminal portions or in the nuclei in them. This result suggests that regeneration of the salivary glands occurs by the formation of new end portions within the boundaries of the remaining portion of the gland, and not as a result of an increase in their size.(Presented by Active Member AMN SSSR A. V. Lebedinskii) Translated from Byulleten' Éksperimental' noi Biologii i Meditsiny, Vol. 51, No. 5, pp. 92–94.     

涎腺导管上皮细胞体外感染HCMV模型的建立

目的　建立涎腺导管上皮细胞体外人巨细胞病毒 (HCMV)感染模型。方法　用免疫细胞化学方法初步鉴定涎腺导管上皮细胞 (HSG)角蛋白 8(cytokeratin 8,CK8)和角蛋白 18(CK18)抗原的表达 ;观察HCMV感染HSG后导致的病变 ;观察宿主细胞中病毒颗粒的超微结构 ;用RT PCR及nest RT PCR检测HCMVIE1(即刻早期 1) /IE2基因的转录 ;用免疫细胞化学法检测HCMV感染细胞中IE1/IE2蛋白的表达。结果　呈上皮样贴壁生长的HSGCK8和CK18阳性表达 ;HCMV感染后 12小时 ( 12h .p .i.)即可见细胞病变 ,6 0h .p .i.CPE已极为明显 ,72h .p .i.绝大部分细胞出现病变。感染的HSG细胞在细胞核、内质网、细胞质中出现数量不等的 3种不同形态的疱疹病毒样颗粒。宿主细胞中可检测到HCMVIE1/IE2的转录以及IE1/IE2蛋白的表达。结论　成功建立了涎腺导管上皮细胞体外HCMV感染模型     

感染HCMV的腮腺导管上皮细胞CK和EMA丢失

目的 研究人类巨细胞病毒(HCMV)感染对腮腺导管上皮细胞表型产生的影响。方法 用免疫组化方法检测腮腺巨细胞包涵体病石蜡包埋组织中巨细胞病毒以及早期抗原、CK、EMA等的表达．结果 腮腺导管上皮细胞感染人巨细胞病毒后，作为上皮性标志物的CK和EMA表达呈阴性。结论 人巨细胞病毒感染腮腺导管上皮细胞使其CK和EMA丢失。单层上皮角蛋白网具有维持上皮细胞机械力学完整性的功能。     

Ultrastructural study of acinar and intercalated duct organization of submandibular and parotid salivary gland

According to some current hypotheses, the morphology and organization of the intercalated duct/acinar interface of salivary gland have implications for the induction of tumors in this organ. However, this region has received limited detailed investigation. To study the organization of the terminal ductal segments of salivary gland, conventional transmission electron microscopy of human parotid and submandibular glands and canine submandibular gland was combined with 3-dimensional observations of polymer casts of the canine submandibular ductal system; the latter were prepared by retrograde injection of acrylic resin via the main excretory duct with subsequent digestion of the gland tissue. The division of intercalated ducts, into first- and second-order branches, and acinar arrangement is more complex than previously suggested. The entire surface of each elongated second-order intercalated duct is covered with acini projecting in all directions. In the human gland, some acini abut directly on the intercalated duct surface, whereas others are connected by a short stalk of intercalated duct cells; in comparison with canine submandibular gland, the latter may be a modification producing a third-order of the intercalated duct unit. All of these features combine to produce a highly efficient secretory apparatus with a large proportion of acinar cells to each intercalated duct.     

Low-grade mucoepidermoid carcinoma of salivary glands: characteristic immunohistochemical profile and evidence of striated duct differentiation

The purpose of the present study is to determine the presence and distribution of epithelial and myoepithelial cells in mucoepidermoid carcinoma (MEC) of salivary glands and to compare them with normal salivary gland tissue and other primary carcinomas. This is in order to establish novel diagnostic criteria and to better understand MEC histogenesis. Formalin-fixed paraffin-embedded tissues from ten well-differentiated MECs, three adenoid cystic carcinomas (ACC), four acinic cell carcinomas (AC), and three epithelial-myoepithelial carcinomas (EMCC) of salivary glands were studied with immunohistochemistry using antibodies that recognise antigens indicative of epithelial and myoepithelial cell differentiation. An anti-mitochondrial antibody was also employed. Normal salivary tissue was present for comparative study in non-tumorous areas of the same section from 12 cases. MEC contained numerous keratin-positive cells. Anti mitochondrial antibody was diffusely positive in all ten of these tumours. Smooth muscle actin, h-caldesmon, and smooth muscle heavy chain myosin, which are indicative of myoepithelial cell differentiation, were negative. Rare cells in only one case were stained by calponin. Cytokeratin 14 (CK14) and anti mitochondrial antibody stained cells located mainly at the periphery of neoplastic nests and cystic spaces, while CK7 was mainly present in cells bordering gland lumina (zoning pattern). The immunohistochemical cell profile was similar to that seen in striated normal ducts. All others tumours studied showed a different immunohistochemical pattern, mostly consisting of a lack of mitochondrion-rich cells and the presence of myoepithelial cells in ACC and EMCC. Immunoreactivity in MEC for CK7, CK14 and mitochondrial antibodies appears as a peculiar pattern of staining, different from that of other salivary gland tumors; this seems helpful for diagnostic purposes. In addition, a differentiation of the "striated duct phenotype" is suggested.     

Synthesis of secretory and plasma membrane glycoproteins by striated duct cellsof rat salivary glands as visualized by radioautography after 3H-fucose injection

The ability of the striated ducts of rat salivary glands to incorporate ³H-fucose into glycoprotein was studied by light and electron microscope radioautography. At 3.5 to 20 minutes after intravenous injection, the majority of the radioautographic grains in the ducts of the parotid gland were localized to the Golgi apparatus. By 40 minutes, the percentage of grains over the Golgi apparatus had decreased; a corresponding increase in grains occurred over small (0.1-0.4 μm) apical granules and the highly infolded basal and lateral plasma membranes. By two hours, less than 10% of the label was associated with the Golgi apparatus, while 26% and 28% were attributed to the apical granules and plasma membrane, respectively. By 8 to 12 hours after injection, the number of grains over the apical cytoplasm had decreased, suggesting luminal discharge of the apical granules. In contrast, the basal and lateral plasma membranes remained labeled up to 30 hours after injection as judged by the distribution of grains in light microscope radioautographs. Mitochondria appeared capable of independent incorporation of fucose, accounting for about 20% of the grains from ten minutes to two hours after injection. Comparable results were obtained in the striated ducts of the submandibular and sublingual glands. These results indicate that the striated duct cells readily incorporate ³H-fucose into newly-synthesized glycoproteins. A portion of these are secretory glycoproteins which are packaged and stored in the apical granules, and a portion are membrane glycoproteins which are incorporated into the extensive plasma membrane of these cells.     

Ductal adenomas of salivary gland showing features of striated duct differentiation ('striated duct adenoma'): a report of six cases

Weinreb I, Simpson R H, Skálová A, Perez‐Ordoñez B, Dardick I, Chetty R & Hunt J L
(2010) Histopathology 57 , 707–715
Ductal adenomas of salivary gland showing features of striated duct differentiation (‘striated duct adenoma’): a report of six cases Aims: To describe a salivary adenoma composed largely of unilayered ducts resembling striated ducts, and to differentiate it from similar adenomas, including canalicular and intercalated duct adenoma. Methods and results: Six unilayered ductal adenomas were identified in parotid (four) and palate (two). They were encapsulated, ranged from 0.5 to 3.0 cm and composed of closely apposed ducts with virtually no stroma. The ducts varied in size and showed cysts up to 0.1 cm. The cells were eosinophilic and bland. Prominent cell membranes, reminiscent of ‘striations’ of normal striated ducts, were seen. The typical epithelial ‘beading’ pattern with abundant stroma of canalicular adenoma was absent. The tumours expressed keratins (six of six) and S100 (five of six). Smooth muscle actin (SMA) revealed no myoepithelial cells. Two tumours showed focal bilayered ducts with calponin or smooth muscle myosin heavy chain, but the tumours were largely unilayered. Only isolated cells in three tumours were positive with p63; a pattern identical to striated ducts. In contrast, the normal excretory and intercalated ducts all contained diffuse bilayering with basal or myoepithelial markers. Conclusions: Striated duct adenomas are unilayered ductal tumours that recapitulate normal striated ducts.     

Low-grade salivary duct carcinoma of the parotid gland: report of a case with immunohistochemical analysis

Salivary duct carcinoma (SDC) is a highly aggressive malignancy of the salivary glands. However, one type of SDC, which shows minimal invasion and better prognosis, is known as low-grade SDC (LG-SDC). This report presents an additional case of LG-SDC of the parotid gland. The patient was a 38-year-old Japanese woman who noticed painless swelling of the left parotid region. Grossly, the cut surface of the tumor was cystic. Microscopically, the tumor showed a multicystic pattern, which was lined by eosinophilic to clear atypical cells with cribriform or Roman bridge patterns. An immunohistochemical examination revealed the tumor was positive for cytokeratin (CK) 7 and epithelial membrane antigen, partially positive for androgen receptor and gross cystic disease fluid protein-15, and diffusely positive for Her-2/Neu, progesterone, and estrogen receptors. The cancer cells showed focal immunopositivity for S-100 protein. Immunostaining for p63, CK14, and calponin showed an in situ pattern in most areas of this tumor, whereas the tumor showed minimal invasion. The cancer cells were diffusely positive for MUC1 and MUC6 and focally positive for MUC2 and MUC4. Finally, the tumor was diagnosed to be LG-SDC. The differential diagnosis and the mucin pattern were evaluated.     

Intercalated duct cells in the rat parotid gland may behave as tissue stem cells

This study was conducted to determine whether intercalated duct cells in the rat parotid gland have the properties of tissue stem cells. After induction of cellular proliferation by repeated administration of isoproterenol (IPR), a β-adrenergic agonist, proliferation activity in acinar, intralobular, and intercalated ductal cells was quantified using Ki-67 immunohistochemistry. The total number of each type of component cell in a gland was also estimated in the course of IPR treatment. IPR was found to induce proliferation of acinar and intercalated duct cells, but not intralobular duct cells. The total number of acinar cells in a gland on day 5 of IPR treatment was 1.6 times of that at day 0 (baseline). In contrast, the total numbers of intercalated and intralobular duct cells did not change from baseline, indicating a high possibility that the proliferated intercalated duct cells differentiated into acinar cells. On days 2 to 3 of IPR treatment, intercalated duct cells with amylase-positive secretory granules were recognized in a region very close to the acini, and were suspected of being transitional cells from intercalated duct to acinar cells. This quantitative study indicates that intercalated duct cells may have the properties of tissue stem cells upon IPR stimulation.     

Morphological study of the fetal parotid duct and buccinator muscle and the relationship to salivary secretion

The parotid glands secrete about 25% of all saliva produced. In the presence of a stimulus, the amount of saliva secreted from the parotid gland increases to 50%. A decrease in the amount of produced saliva due to aging and parotiditis results in a dry mouth. Therefore, the parotid duct is important to maintaining a healthy oral cavity. In human adults, the parotid duct, ～6–8‐cm long, travels over the masseter muscle and penetrates the buccinator muscle to enter the oral cavity. Although there have been various studies regarding the parotid gland, only few suggest a functional role of the parotid duct, especially its area of penetration of the buccinator muscle. In this study, 34 fetal specimens ranging from 4 to 10 months of age at death were dissected for anatomical and histological examinations. The area of the parotid duct penetrating the buccinator muscle was fully formed in 5‐month‐old fetuses. This study found buccinator muscle fibers invading the parotid duct wall near its opening in 6‐month‐old fetuses and older. Our results support the claim that the buccinator muscle may act as a sphincter, playing a role in regulating and possibly preventing the reflux of salivary secretions into the parotid duct. Clin. Anat. 23:642–648, 2010. © 2010 Wiley‐Liss, Inc.