Intercalated Duct Research Articles

Androgens and Integrins in Salivary Glands in Sjögren’s Syndrome

Laminin alpha1-chain normally induces intercalated duct progenitors to differentiate to acinar cells through integrin (INT) alpha1ss1 and alpha2ss1 receptors. Maintenance of acinar cells is impaired in Sjögren's syndrome (SS), which is also characterized by low levels of serum and salivary androgens. We hypothesized that androgens normally support salivary gland remodeling by upregulating either laminin alpha1 chain or its cellular alpha1 or alpha2 INT subunit-containing receptors. Intercalated duct and acinar human salivary gland (HSG) cells and labial salivary gland (LSG) biopsies from healthy controls and patients with SS were cultured without or with sex steroids. Laminin alpha1 chain and INT alpha1 and alpha2 subunits were studied using quantitative reverse-transcription real-time polymerase chain reaction and INT alpha1 and alpha2 subunits using immunofluorescence staining. INT alpha1-subunit and alpha2-subunit messenger RNA (mRNA) levels were increased in intercalated duct and acinar cells by DHEA and testosterone. In contrast, laminin alpha1-chain mRNA levels were not affected. The upregulating effect of DHEA on INT subunits was also seen at the protein level. DHEA also increased mRNA levels of both INT subunits in healthy but not SS LSG. Androgens increased INT alpha1 and alpha2 subunits in tubuloepithelial cells and in healthy LSG, but in SS salivary glands this androgen regulation was defective, which is likely to contribute to defective outside-in signaling, acinar atrophy, and ductal cell hyperplasia.

Functional Vanilloid Receptor-1 in Human Submandibular Glands

Vanilloid receptor-1 (VR1) was originally found in the nervous system. Recent evidence indicates that VR1 is also expressed in various cell types. We hypothesized that VR1 exists in the human submandibular gland (SMG) and is involved in regulating salivary secretion. VR1 mRNA and protein were expressed in human SMGs and a human salivary intercalated duct cell line. VR1 was mainly located in serous acinar and ductal cells, but not in mucous acinar cells. Capsaicin, an agonist of VR1, increased intracellular free calcium, enhanced phosphorylation of extracellular signal-regulated kinase, and induced the trafficking of aquaporin 5 (AQP5) from the cytoplasm to the plasma membrane. These effects were abolished by pre-treatment with the VR1 antagonist capsazepine. Furthermore, capsaicin cream applied to the skin covering the submandibular area increased salivary secretion. These findings indicated that a functional VR1 is expressed in the human SMG and is involved in regulating salivary secretion by mediating AQP5 trafficking.

The Structure of Tight Junctions in Mouse Submandibular Gland

Salivary gland cells are joined by junctional complexes consisting of a tight junction (TJ), zonula adherens and one or more desmosomes. TJs regulate paracellular permeability, maintain separate apical and basolateral membrane domains, and serve as signaling centers. We examined TJs of mouse submandibular glands (SMG) in thin sections and freeze-fracture replicas. TJs between acinar cells and between intercalated duct cells had 2-6 parallel strands on the protoplasmic fracture face, with occasional branches, interconnections and free ends, and corresponding grooves on the extracellular face. Granular duct cell TJs had 2-30 strands, a depth of <or=0.5 microm, and occasional loops extending further basally. Where 3 or 4 cells met, the TJs extended basally <or=1 microm and consisted of 2 parallel boundary strands into which the apical strands inserted. Quantitative analyses showed significant differences in TJ complexity, measured by fractal geometry, and strand number of acinar compared to granular duct cells, and a greater number of strands in male compared to female granular ducts. Pilocarpine stimulation increased TJ strand number in female acinar cells, and increased complexity of male granular duct cell TJs. As the salivary gland water channel aquaporin 5 (AQP5) has been proposed to functionally interact with TJs to regulate salivary fluid composition, we also studied glands from AQP5 knock-out mice. In males lacking AQP5, granular duct TJs were more complex than those of wild-type mice, and exhibited more strands following pilocarpine stimulation. The results demonstrate specific gender, cell type and genetic differences in TJ structure and response to stimulation.

Malignant salivary gland tumors and cyclo-oxygenase-2: A histopathological and immunohistochemical analysis with implications on histogenesis

The classification system for malignant salivary gland tumors (MST) is largely dependent on its histogenesis. The histogenesis is uncertain but the "bicellular theory of origin" has been accepted by most and states that malignant transformation of reserve cells from either the intercalated or excretory duct are responsible for the development of MST. Cyclooxygenase-2 (cox-2), a potential molecular marker for MST, was analyzed on a series (n=56) of MST with the aim of determining the morphological MST subtypes capable of cox-2 overexpression and correlating its expression with histogenesis. Fifty six primary major and minor gland MST were stained with anti-cox-2 antibody and rated with a combined score that added a scale of intensity to the percentage of tumor cells that overexpressed the cox-2 protein. A score of <3: negligible or negative staining; score of 4-5; moderate staining; score of 6-7; strong staining. Tumor types were segregated by morphology, histological features and proposed histogenesis. Strong cox-2 overexpression was noted in all MST of proposed excretory duct origin: salivary duct carcinoma (100%), mucoepidermoid carcinoma (MEC) (92%), and adenocarcinoma nos (AdC nos) (83%). Primary squamous cell carcinoma (PSCC) was the exception. Negative expression was noted in all tumors of proposed intercalated duct origin (adenoid cystic carcinoma, basal cell adenocarcinoma and acinic cell carcinoma) with the exception of one case of polymorphous low grade adenocarcinoma. Strong cox-2 overexpression was noted in the epidermoid cells of MEC, abluminal duct cells surrounding the duct-like structures and ductal cells of AdC nos and salivary duct carcinoma. Myoepithelial and acinar cells were unreactive. Although preliminary, the results of our study support the concept that MST of proposed excretory duct origin share a common histogenesis. Negligible cox-2 expression in PSCC may provide a useful tool for diagnosing the often histologically indistinguishable cases of high grade MEC. Follow-up studies on a larger series of MST are warranted.

Intercalated Duct Lesions of Salivary Gland

Intercalated duct lesions (IDLs) are rare, poorly understood and not well-studied lesions that have been associated with a small number of epithelial-myoepithelial carcinomas (EMC) and basal cell adenomas. To examine the nature of IDLs and their association with salivary gland tumors, we reviewed 34 lesions in 32 patients. The IDLs were stained with CK7, estrogen receptors (ER), progesterone receptors, lysozyme, S100, calponin, and CK14. The patients ranged in age from 19 to 80 years (mean 53.8) with a 1.7:1 female predominance. The majorities of IDLs were parotid lesions (82%), were small and nodular (average size 3.1 mm) and showed 3 architectural patterns: hyperplasia (20), adenoma (9), and hybrid forms (5). In 59% of cases, IDLs were seen in conjunction with another salivary gland tumor, most commonly basal cell adenoma (8 cases), followed by EMC (3 cases). One case showed a combination of intercalated duct hyperplasia and basal cell adenoma. The IDLs stained diffusely with CK7 (100%) and S100 (73%) and focally for ER (91%) and lysozyme (100%). Calponin and CK14 highlighted a thin myoepithelial cell layer around all ducts (100%). Normal intercalated ducts were also consistently positive for CK7 and lysozyme, and focally for ER, but were S100 negative. In summary, IDLs have a variety of patterns ranging from hyperplasia to adenoma with hybrid lesions and share morphologic and immunophenotypic features with normal intercalated ducts. There is an association with basal cell adenomas and EMC, which lends credence to their role as a putative precursor lesion.

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 beta-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 and functional differentiation of HSG cells: Role of extracellular matrix and trpc 1

A human salivary intercalated duct cell line (HSG) is capable of morphological change to acinar-type cells, and of salivary amylase (AMY1) expression, by culturing on basement membrane extracts (BME). The aim of this study was to determine the critical conditions for functional and morphological differentiation of HSG cells and to establish if the processes are related. Cells were grown on BMEs that had different protein concentrations and growth factor content, and then examined with respect to morphology and AMY1 expression. To investigate the role of intracellular calcium in amylase expression, a pcDNA3.1-TRPC1alpha construct was used to overexpress htrp1alpha, which mediates the store-operated calcium entry in HSG cells. Expression of the AMY1, TRPC1alpha and beta genes was quantified by means of real time RT-PCR. Growth factor-reduced BME (12.8 mg/ml) induced multicellular acinar structures with lumen formation but without stimulation of either AMY1 or TRPC1. HSG cells cultured on higher concentration BME (17.5 or 16.4 mg/ml) formed reticular networks. AMY1 expression increased both on growth factor-reduced BME (17.5 mg/ml: 3.0-fold, P < 0.001) and on regular BME (16.4 mg/ml: 3.7-fold, P < 0.001) accompanied by a slight increase in expression of TRPC1alpha and TRPC1beta. Overexpression of htrp1alpha did not cause any significant changes in AMY expression, though it attenuated the BME (17.5 mg/ml)-induced AMY1 upregulation. Overall, the higher protein concentration BME favors amylase expression in HSG cells, whereas the lower concentration causes marked morphological changes.

Squamoid Cyst of Pancreatic Ducts: A Distinct Type of Cystic Lesion in the Pancreas

The clinicopathologic features of a hitherto unrecognized cystic tumor of the pancreas are documented, and its possible relationship to a more common incidental microscopic lesion is analyzed. Six patients (3 men and 3 women) had undergone resection specifically for this cyst type. The mean age of the patients was 63 years (range 52 to 79 y) and the mean size of the tumors was 2.6 cm (median 1.5, range 0.8 to 9 cm). The cysts had variable lining ranging from attenuated, flat squamoid cells to transitional, to stratified squamous without keratinization (no granular layer). The cells forming the basal/parabasal region expressed p63 (transitional/squamous cell marker, not detected in any normal pancreas or nonsquamous neoplasia) and the surface cells were positive for MUC 1 and MUC 6 (markers present in intercalated duct cells), and negative for GLUT-1 (consistent marker of serous adenomas). The lesions appeared to be unilocular cystic dilatation of the ducts that typically contained distinctive muco-proteinaceous acidophilic acinar secretions forming concretions, confirming their communication with the acinar system, and suggesting a localized obstruction in their pathogenesis (a form of "retention" cyst). A thin fibrous wall devoid of any lymphoid tissue separated the cysts from unremarkable parenchyma. There was no evidence of pancreatitis (fibrosis or inflammation). Separately, 110 pancreata resected for various reasons were analyzed, and what seems to be microscopic/incidental version of this process was identified in 10 examples (8%). These microcysts were found lying within compact acinar tissue, and appeared to be transforming from intercalated ducts, some focally connected to acinar elements, and they had abortive (nonbridging) septae with pseudo-loculated appearance, irregular contours and often showed tightly packed clusters of ducts with similar morphology described in the cases underwent resection specifically for this cyst type. In conclusion, the distinctive morphologic, immunophenotypic, and clinical characteristics of this cystic lesion warrant its classification as a separate entity. We propose to refer to it as squamoid cyst of pancreatic ducts. It seems to be a metaplastic cystic transformation beginning in the intercalated ducts. Although obstructive etiology is suspected, a specific factor or surrogate evidence of obstruction such as chronic pancreatitis is typically lacking.

A proteomics approach to characterizing human submandibular gland cell lines by fluorescent two-dimensional differential in-gel electrophoresis

The human salivary glands have a variety of histologic features such as intercalated duct cells, myoepithelial cells and acinar cells. A neoplastic human salivary intercalated duct cell line (HSG) and its derivatives, HSG with a myoepithelial cell phenotype (HSG-AZA1) and HSG with an acinar cell phenotype (HSG-AZA3) induced by 5-aza-2'-dC treatment of HSG cells, have been reported. To identify characterization of intercalated duct cells, myoepithelial cells and acinar cells in the salivary gland, we selected HSG, HSG-AZA1 and HSG-AZA3 cell lines to perform two-dimensional electrophoresis analysis. We used a fluorescent two-dimensional differential in-gel electrophoresis (2-D-DIGE) for comparative proteomics, which improved the reproducibility and reliability of differential protein expression analysis between the samples. Furthermore, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) peptide mass fingerprinting (PMF) was used to identify the proteins. These methods were combined to approach the protein profiles associated with characterization between HSG, HSG-AZA1 and HSG-AZA3 cells. Using these strategies, we identified seven HSG associated proteins, such as actin-beta, hydrocephalus inducing protein, L-plastin, KIAA0657 protein, septin 6 isoform A, lamin A/C isoform 2 and superoxide dismutase 2, three HSG-AZA1 associated proteins such as ubiquitin carboxyl-terminal esterase L1, myosin light chain 2 and muscle creatine kinase, and two HSG-AZA3 associated proteins, microtubule-associated protein 6 and Annexin A3. These results suggest that the proteins are associated with characterization of the salivary gland.

CD56 (NCAM) Expression in Pancreatic Carcinoma and the Surrounding Pancreatic Tissue

Expression of CD56, also known as the neural cell adhesion molecule (NCAM), in the pancreatic ducts of chronic pancreatitis is considered to represent a regenerative process of the pancreatic duct system. CD56 expression was analyzed in 25 tissue samples of invasive ductal carcinoma without mixed ductal-endocrine carcinoma of the pancreas, and in the surrounding non-cancerous pancreatic tissue. CD56 expression was detected in intercalated ducts (ICDs) of lobules in the pancreatic parenchyma showing chronic inflammation close to the carcinoma, but not in the carcinoma itself, in all cases. CD56 showed strong, diffuse expression in the areas with severe inflammation, but expression was weak in ICDs where the inflammation was mild. We suggested that CD56 expression is degenerative process in pancreatic tissue with chronic inflammation, and that examination of CD56 expression may be helpful in the differentiation of atypical degenerative ducts from cancerous ducts.

Imbalance between apoptosis and proliferation causes late radiation damage of salivary gland in mouse

Severe xerostomia is a common late radiation consequence, which occurs after irradiation of head and neck malignancies. The aim of the present study was to analyze apoptosis and proliferation and their relationship during the late post-irradiation phase. C57BL/6 mice were locally irradiated in head and neck region with a single dose of 7.5 or 15 Gy and their submandibular glands were collected at 40 and 90 days after irradiation. To identify apoptotic cells, the TUNEL method was employed and immunohistochemistry with proliferating cell nuclear antigen (PCNA) was used for detecting proliferation. Histological changes at day 40 were mild in contrast to day 90 when glands of irradiated mice showed severe atrophy, vacuolization and mononuclear infiltration. Acinar cells, granular and intercalated duct cells of mice irradiated with 7.5 and 15 Gy expressed higher apoptotic index than cells of non-irradiated, control glands at both examined time points. At 40 days, a higher proliferation index in granular and intercalated duct cells was detected only in group irradiated with 7.5 Gy. At 90 days, proliferation index for all cell types in both irradiated groups was similar to the controls. According to our results, the imbalance between apoptosis and proliferation caused by X-irradiation may be the reason for gland impairment during the late post-irradiation phase.

Three-Dimensional Structure of Peripheral Exocrine Gland in Rat Pancreas

The purpose of this study was to elucidate the 3-dimensional structure of the peripheral pancreatic exocrine gland. We observed serial sections of rat pancreatic tissue using a transmission electron microscope and traced the intercalated duct lumina, intra-acinar secretory canaliculi, intercalated duct cells or centroacinar cells, and basement membranes of acini onto a transparent sheet. These traced diagrams were reconstructed. The intra-acinar secretory canaliculus had branches but no anastomosis. The intercellular secretory canaliculus was extended from the central lumen through the space between the lateral surfaces of the acinar cells to the acinar base. Furthermore, the cytoplasmic process of each centroacinar cell was extended along the central lumen and connected to an intercalated duct cell; thus, centroacinar cells with the same structure as intercalated duct cells were not isolated from the intercalated duct cells. In this study, we elucidated the normal 3-dimensional structure of the peripheral pancreatic exocrine gland. To understand the pathogenesis of chronic pancreatitis, in the future we intend to examine the morphologic changes of pancreatic tissue during the onset and advancement of chronic pancreatitis using animal models.

Morphological Changes in the Rat Endocrine Pancreas within 12 h of Intravenous Streptozotocin Administration

We examined early morphological changes in pancreatic endocrine cells within 12 h of intravenous streptozotocin (STZ) administration (60 mg/kg). Thirty rats were allocated either to a control group (vehicle alone) or to one of four experimental groups tested after 3, 6, 9 and 12 h. Karyopyknosis and cytoplasmic vacuoles were first observed in beta-cell cytoplasm 3 h after STZ administration (STZ-3 h), and the most severe damage was found in beta cells at STZ-12 h. Insulin-positive non-islet cells were observed near the intercalated duct (ICD) and/or centroacinar (CA) cells at STZ-6 h and their numbers peaked at STZ-6 h. The distribution patterns of the insulin-positive cells and those of nestin and insulin-like growth factor-1 were similar and their nuclei were positive for proliferating cell nuclear antigen. Thus, ICD cells and/or CA cells reacted immediately to transform into insulin-secreting cells to replace injured beta cells (or to compensate for the lack of beta cells) within 12 h of STZ administration.

Intercalated duct cell is starting point in development of pancreatic ductal carcinoma?

BackgroundAlthough it is well known that the pancreatic ductal carcinoma may develop having a relationship to the mucous gland hyperplasia (MGH) with atypia (PanIN-1B by PanIN system), the starting point of this atypical MGH is unclear. To know it, we examined the pancreas tissue using many methods described below.Methods1. Twenty-seven surgically resected pancreas tissue specimens, including pancreatic ductal carcinomas (PDC), chronic pancreatitis and normal pancreas, were investigated using immunohistochemical stainings for MUC1, MUC6, 45M1, Ki67 and p53. 2. DNA extraction and analysis of K-ras mutation at codon 12 using microdissection method: The paraffin blocks with 16 regions including the intercalated duct cell (IC) adjacant to the atypical MGH were prepared for DNA extraction. Mutation of K-ras codon 12 was analized and compared in enriched polymerase chain reaction-enzyme-linked minisequence assay (PCR-ELMA).Results1. In the normal pancreas, although no positive cell was seen in 45M1, p53, Ki67, the cytoplasm of IC were always positive for MUC1 and sometimes positive for MUC6. In the pancreas with fibrosis or inflammation, MGH was positive for MUC6 and 45M1. And atypical MGH was positive for MUC1, MUC6 and 45M1. Some IC adjacent to the atypical MGH was positive for Ki67 as well as atypical MGH. The carcinoma cells in all cases of PDC were diffusely positive for MUC1, 45M1, p53 and Ki67, and focally positive for MUC6. 2. In K-ras mutation, we examined the regions including IC adjacent to the atypical MGH, because the immunohistochemical apomucin stainings of these regions resembled those of PDC as decribed above. And K-ras mutation was confirmed in 12 of 16 regions (75%). All mutations were a single mutation, in 6 regions GTT was detected, in 4 regions GAT was detected and in 2 region AGT was detected.ConclusionSome intercalated duct cell may be the starting point of the pancreatic ductal carcinoma, because the exhibitions of mucin expressions, Ki67, p53 and K-ras mutation in some intercalated duct cell resembled those of mucous gland hyperplasia or pancreatic ductal carcinoma.

Expression and localization of the transcription factor JunD in the duct system of mouse submandibular gland.

We studied the expression and localization of JunD, a component of the transcription factor activator protein-1 (AP-1), in the mouse submandibular gland with immunoblotting and immunohistochemistry. In adult mice, all seven Jun and Fos family members constituting the AP-1 complex were expressed more abundantly in the female gland than in the male gland, and JunD was the most abundant of the members. Immunoreactivity for JunD was localized exclusively in the duct system of the gland, in which it was localized to the nuclei of intercalated duct (ID) cells and a subpopulation of striated duct (SD) cells located adjacent to ID. In contrast, granular convoluted tubule (GCT) cells, which are much more abundant in the male gland, were devoid of JunD. During postnatal development of the male gland, JunD was lost from the duct cells as they differentiated to GCT cells at 3-5 weeks postpartum. When GCT differentiation was induced in adult female gland by testosterone administration, many JunD-negative SD cells were temporarily induced to express JunD after 6-24 hr, but those cells lost JunD as they completely converted to GCT cells by 48 hr. These results suggested that JunD is involved in the differentiation of the duct system of mouse submandibular gland, in which there is crosstalk between the androgen/androgen receptor system and the AP-1 complex.

Immunocytochemical localization of histatins in human salivary glands.

Histatins are a family of salivary proteins with bactericidal and fungicidal activities that contribute to the innate defense of the oral cavity. Histatins are present in the serous granules of the parotid and submandibular glands. The important role of histatins in saliva, and the limited information on their cellular and subcellular distribution, prompted us to further define the localization of histatins in the major salivary glands. Immunogold-silver staining of 1- micro m sections of plastic-embedded tissue with anti-histatin antibody revealed histatin immunoreactivity in the serous acinar cells of the parotid and submandibular glands, the serous demilune cells of the submandibular and sublingual glands, and in occasional intercalated duct cells. No reactivity was seen in mucous cells or in striated or excretory duct cells. Electron microscopic observations of thin sections labeled with anti-histatin and gold-labeled secondary antibodies revealed immunoreactivity associated with the rough endoplasmic reticulum and Golgi complex and in secretory granules of serous acinar and demilune cells. The granules of parotid acinar cells exhibited relatively uniform labeling of their content, whereas the granules of serous cells in the submandibular and sublingual glands showed variable labeling of the dense and light regions of their content. A few intercalated duct cells adjacent to the acinar cells also exhibited labeled granules. These results suggest that the serous cells of the major glands are the main source of histatins in human saliva. They are also consistent with several previous studies demonstrating the variable distribution of different proteins within the granule content.

Immunolocalization of AQP-5 in rat parotid and submandibular salivary glands after stimulation or inhibition of secretion in vivo

In vitro studies of cultured salivary gland cells and gland slices have indicated that there may be regulated translocation of aquaporin (AQP)-5 between the apical plasma membrane and intracellular compartments of the secretory cells. However, it remains unknown whether AQP-5 in salivary glands is subject to regulated trafficking in vivo. To examine this possibility, we have investigated the subcellular localization of AQP-5 in rat parotid and submandibular glands fixed in vivo under conditions of stimulated or inhibited salivary secretion. Immunofluorescence and immunoelectron microscopy was used to determine the subcellular distribution of AQP-5 in control conditions following the stimulation of secretion with pilocarpine (a muscarinic agonist) or epinephrine (an alpha-adrenoceptor agonist) or during inhibition of basal secretion with atropine (a muscarinic antagonist) or phentolamine (an alpha-adrenoceptor antagonist). Under control conditions, >90% of AQP-5 was associated with the apical plasma membrane of acinar and intercalated duct cells, with only rare gold particles associated with intracellular membrane domains. Pilocarpine treatment dramatically increased saliva production but had no discernible effect on AQP-5 distribution. However, the increased salivary secretion was associated with luminal dilation and the appearance of a markedly punctate AQP-5 labeling pattern due to clustering of AQP-5 at the microvilli (especially evident in the parotid gland) after 10 min of drug injection. No changes in the subcellular localization of AQP-5 were seen in response to epinephrine, atropine, or phentolamine treatment compared with control tissues. Thus AQP-5 is localized predominantly in the apical plasma membrane under control conditions, and neither the onset nor the cessation of secretion is associated in vivo with any significant short-term translocation of AQP-5 between intracellular structures and the apical plasma membrane.

Expression of nestin and IGF-1 in rat pancreas after streptozotocin administration.

The present study examines whether centroacinar (CA) and intercalated duct (ICD) cells can serve as stem cells, after administration of the diabetogenic agent streptozotocin (STZ). Thirty rats were divided into five experimental groups: (1) control, (2) 1 day after STZ (STZ-1), (3) 3 days after STZ (STZ-3), (4) 7 days after STZ (STZ-7) and (5) 14 days after STZ (STZ-14). Many small pancreatic islets were observed in the STZ-7 group than in the other experimental groups, and many of these small islets were in close contact with ICD and CA cells. A higher number of nestin, insulin-like growth factor-1 (IGF-1) and IGF-1-receptor positive ICD and CA cells were observed at STZ-3 and STZ-7 than at the others. These expression patterns coincided well with the proliferating cell nuclear antigen pattern. The results suggest that rat pancreatic endocrine cells after damage by STZ administration might be recovered from newly generated cells derived from ICD and CA cells.

Immunohistochemical distribution of CD9 in parotid gland tumors

Objective: CD9 is a member of the tetra-membrane-spanning glycoprotein family called tetraspanin. CD9 suppresses breeding and motion in some types of cancer cells. At present, the expression of CD9 in the salivary gland has not yet been elucidated. Methods: We examined the expression of CD9 not only in the normal salivary glands of human embryo and adults but also in the parotid gland tumors using immunohistochemical staining. Results: CD9 was not detected in embryos at 18 weeks of gestation, but was observed at 24 weeks in the salivary gland. CD9 was constantly detected in the adult normal parotid gland. In benign parotid gland tumors, CD9 was present in the 11 of 16 pleomorphic adenomas, every Warthin tumors (18/18) and basal cell adenoma (1/1). In contrast, positive staining for CD9 in malignant parotid tumors was observed in only the case of mucoepidermoid carcinomas. Neither acinic cell carcinomas or adenoid cystic carcinomas did show positive reaction in examined cases. The localization of CD9 was also observed in intercalated duct cells. Conclusion: There was a statistically significant reduced expression of CD9 in malignant parotid gland tumors as compared to benign parotid gland tumors ( P=0.003).

Thyroid hormone regulation of granular intercalated duct cells in the submandibular glands of female mice.

Intercalated ducts (IDs) in the submandibular glands (SMGs) of mice exhibit a sexual dimorphism, in which a few cells in the IDs of females, but not of males, possess secretory granules. The effects of a hypophysectomy (Hypox) followed by the administration of triiodo- l-thyronine (T3) on such granular intercalated duct (GID) cells in the female gland were histologically examined. Semithin sections stained with Heidenhain's iron hematoxylin revealed that Hypox resulted in the complete disappearance of the GID cells. In Hypox females, electron-microscopy examination of the ID cells whose localization corresponded to that of the GID cells in normal females showed that these cells had a pale, centric nucleus, poorly developed rough-surfaced endoplasmic reticulum (RER) and Golgi apparatus, and no secretory granules. When T3 (1 mg/kg body weight) was given to Hypox female mice every other day for 2 weeks, the GID cells reappeared in most of the ID segments. Electron microscopy revealed that these cells had abundant secretory granules in their apical cytoplasm, a nucleus located near the base of the cell, and layered cisterna of RER and segments of Golgi apparatus in the perinuclear cytoplasm. The localization and distribution of the GID cells in the T3-treated Hypox females were almost the same as those in normal females. Taken together, these results suggest that thyroid hormones upregulate the GID phenotype, and that thyroid hormones are essential for the exocrine activities of GID cells.