The histochemistry of mucins in certain primate salivary glands

Submandibular and sublingual salivary glands of squirrel and rhesus monkeys and man contain histochemically demonstrable neutral mucosubstances, sialomucins and sulfomucins. Judged by results obtained with a variety of staining procedures and by the effects of prior sialidase digestion, periodate oxidation and certain chemical modifications on the several staining procedures, differences are revealed in the types of mucosubstances within each cell type. Specifically, sialic acid-containing mucosaccharides are present uniformly in the mucous cells of the submandibular glands of both monkeys and in a posterior segment of the sublingual gland of the rhesus monkey. Sulfomucin is the predominant secretion of the sublingual gland of the squirrel monkey and is also found in the anterior portion of the sublingual of the rhesus monkey as verified by S³⁵O₄ = autoradiography. This latter sulfomucin is admixed with a small amount of sialomucin. One or the other or mixtures of these two mucins in about equal proportions are present in the mucous acini of human submandibular glands. Seromucous acini in the human submandibular gland form a granular secretion with strong affinity for aldehyde fuchsin possibly attributable to a sulfated mucosubstance. Other and perhaps some of the same seromucous acini in this gland produce a granular secretion containing sialic acid in probable proximity, as shown by the periodate-para diamine procedure after sialidase, to a hexose or deoxyhexose. A sulfomucin forms the major secretory component in the mucous acini of human sublingual glands. However, some mucous acini in this sublingual gland produce a mixture of sialo- and sulfomucins either in different or the same cells. Seromucous demilunes or acini in the human sublingual gland produce a granular secretion rich in sialic acid like that in the submandibular gland.     

Structure and carbohydrate histochemistry of postnatal canine salivary glands

Structural changes in secretory units of developing canine salivary glands have been correlated with their histochemically demonstrable carbohydrate content. At birth, three and eight weeks, and six months, secretory cells and duct systems of parotid, submandibular, sublingual and zygomatic glands of mongrel puppies were examined for morphology and localization of sulfomucin, sialomucin, neutral polysaccharide and glycogen. Combining structural and histochemical criteria a classification was formulated to discriminate between mucous, serous, and seromucous cells. Within the first six months of life changes occur in the proportion of these cells in individual salivary glands. Structurally distinct typical and atypical mucous cells contained acidic carbohydrates, usually sulfomucin. In sublingual glands of more mature dogs, however, sialomucin was the predominant constituent in atypical mucous cells. Serous acinar cells containing neutral polysaccharide occurred only in these glands. Seromucous acinar cells secreting acidic carbohydrates, usually sialomucins, were recognized in parotid and zygomatic glands. Demilunes composed of sialomucin-producing seromucous cells and neutral polysaccharide-producing serous cells were observed in submandibular and zygomatic glands, respectively. From this investigation it appears that the structural and carbohydrate profile of developing canine salivary glands is distinctive to the particular age examined.     

Ultrastructure and histochemistry of human anterior lingual salivary glands (glands of blandin and nuhn)

Background: Speciamens of human anterior lingual salivary glans obtained by surgery and by dissection of cadavers were studied ultrastructurally and histochemically. Methods: Specimens were obtained by surgery for ultrastructural study. Other specimens for histochemistry were obtained by dissection of fresh cadavers. Tissues for electron microscopy were fixed and processed by conventional mesns. Formalin-fixed cadaver specimens were subjected to a battery of tests for glycoconjugates. Results: The anterior lingual salivary glands are composed predominantly of mucous tubules (which come in two distinct sizes: large and small), seromucous demilunes, and rare seromucous acini. Regardless of tubule size, mucous cells are typically in appearance and, like mucous cells in other human salivary glands, contain filamentous bodies. Histochemically, the larger tubules contain neutral glycoproteins, low concentrations of sialoglycoproteins, and large amounts of sulfated glycoproteins. The small mucous tubules contain neutral glycoproteins, much sialoglycoprotein, and relatively small amounts of sulfated glycoprotein. The seromucous cells, whether demilunar or acinar, are identical. They contain numerous secretory granules, which show a spectrum of internal patterns from one individual to another. These cells have considerable concentrations of neutral- and sialoglycoproteins and lower concentrations of sulfated gly-coproteins. Countrary to previously published reports, we could find no differences in the ratio of mucous to seromucous cells along the anteriorposterior lingual axis: there was no gradient of seromucous cells in our specimens. The ducts in the anterior lingual salivary glands are not precise counterparts of those in the major salivary glands, since the former have no capsules, hence lack lobulation. Without these familiar structural landmarks, the only duct that can be identified with certainty is the intercalated duct, and then only if it is in continuity with or lies close to a secretory endpiece. Such ducts consist of simple cuboidal epithelium of prosaic appearance. The ductular epithelium gradually thickens and gives rise to what appear to be excretory ducts consisting of columnar cells with few mitochondria. Scattered within the walls of the walls of the larger ducts are patches of typical striated ducts wherein the taller cells display basal striations resulting from highly folded basal plasma membranes and numerous, vertically oriented, virgulate mitochondria. In other atypical regions of the excretory duct, basal cells may have a primary cilium that juts into the intercellular space. Conclusions: There is a high degree of structural variability in human anterior lingual salivary glands. Because of the technical difficulties in collecting pristine saliva from these glands, the precise functions(s) of these organs remains unknown. © 1994 Wiley-Liss, Inc.     

In vivo effects of endotoxin on intraepithelial mucosubstances in rat pulmonary airways. Quantitative histochemistry.

Bacteria-induced bronchopneumonias are often characterized by an influx of neutrophils and excess mucus in pulmonary airways. This study determined how endotoxin, a component of gram-negative bacteria and a potent inflammatory agent, affects the ultrastructure of the mucociliary apparatus and the amount of stored intraepithelial mucosubstances in the main axial airways within the lung. Rats were intranasally instilled, once a day for 3 days, with endotoxin or saline (controls). Animals were sacrificed 1, 2, or 7 days after the last instillation. Microdissected intrapulmonary axial airways (generations 8-11) from the right caudal lobes of infusion-fixed lungs were processed for light and electron microscopy. Morphometric techniques were used to determine the volume densities (Vs) of histochemically stained intraepithelial mucosubstances and numerical densities of airway epithelial cells. There were marked increases, compared with controls, in the amount of intraepithelial mucosubstances in the intrapulmonary axial airways at generations 8 and 11 in the right caudal lobes from endotoxin-instilled rats sacrificed 1, 2, and 7 days after the last instillation. There were significantly greater numbers of surface epithelial cells per length of basal lamina (i.e., hyperplasia) in endotoxin-exposed airways compared with airways from controls. This endotoxin-induced hyperplasia was due primarily to an increase in the number of mucus-secretory cells, which in endotoxin-exposed epithelium were columnar and contained numerous, large confluent, electronlucent, secretory granules composed of acidic and neutral glycoproteins. In contrast, secretory cells in airway epithelium from controls were cuboidal and contained small discrete, electron-dense, granules composed of only neutral glycoproteins. The numbers of ciliated cells and basal cells were similar in both control and endotoxin-exposed epithelium. Only endotoxin-exposed epithelium, however, contained atypical epithelial cells with numerous basal bodies, few cilia, and few apical secretory granules. These results indicate that repeated airway instillations of endotoxin induce an increase in the amount of intraepithelial mucosubstances, secretory cell hyperplasia, and excess luminal mucus in pulmonary airways. Therefore, endotoxin released from gram-negative bacteria may be partially responsible for the structural alterations, in the airway surface epithelium, which result in the excess luminal mucus observed in bacteria-induced bronchopneumonias.     

Epithelial-myoepithelial carcinoma of salivary glands.

Four cases of epithelial-myoepithelial carcinoma of the salivary glands arose as painless masses in patients over 60 years old, three in the parotid and one in the submandibular gland. Histologically, all the tumours were composed of small ducts with a double cell lining surrounded by a basement membrane. The inner cells were epithelial and the outer cells myoepithelial, the latter usually possessing clear cytoplasm. There was a variable degree of intervening hyalinised stroma. All the tumours were partly encapsulated, but also displayed local invasiveness. One of the tumours also showed areas of dedifferentiation when it later recurred and metastasised. The other three were apparently cured by initial excision, with adjuvant radiotherapy in one instance. In the past this tumour has been described as clear cell adenoma, and it was only recently that its true malignant nature, albeit low grade, was recognised. Reports of epithelial-myoepithelial carcinoma are still relatively few, with only one case described from Britain. It is recommended that this histologically distinct neoplasm deserves wider recognition.     

Effect of ultrasound on major salivary glands. Dynamic of morphological changes in rat salivary glands

Morphology of rat submandibular salivary glands was examined before and after 10 sessions of ultrasonic treatment focused onto the gonial angle of the mandibular bone. The employed ultrasound protocol induced adaptive reactions and induced no degenerative and inflammatory processes. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 144, No. 11, pp. 586–589, November, 2007     

Effects of an ambient level of ozone on primate nasal epithelial mucosubstances. Quantitative histochemistry.

Despite the absorption of inhaled oxidant gases by the nasal cavity, little effort has been made to characterize the effects of these oxidants on the nasal mucosa. This study defines the effects of ambient concentrations of ozone on the character and amount of mucosubstances in epithelium of nasal mucosa. Bonnet monkeys were exposed to 0.00 or 0.15 ppm O3 (8 hr/day) for 6 or 90 days, anesthetized, and exsanguinated. Nasal cavities were fixed with Karnovsky's fixative, decalcified, and processed for light microscopy, and sections were stained with alcian blue (pH 2.5)/periodic acid-Schiff or high iron diamine. Volume densities of secretory material in nasal epithelium were determined with the use of a Quantimet 900 image analyzer. After 6 days' exposure there were significant increases in both acidic and neutral glycoconjugates stored in transitional and respiratory epithelium. After 90 days there was significantly less mucosubstance than at 6 days. Only in the transitional epithelium did the total and sulfated mucosubstance remain greater than that of controls. Nasopharyngeal epithelium was minimally affected after 6 days of O3 and unchanged after 90 days. It is concluded that exposures to ambient levels of O3 induce significant changes in the stored secretory product of nasal epithelium.     

In vivo effects of transient neutrophil influx on nasal respiratory epithelial mucosubstances. Quantitative histochemistry.

Certain inhaled toxicants are known to induce mucous hypersecretion in the respiratory epithelium. This secretory change may be a direct effect of the toxicant or an indirect effect of the concomitant inflammatory response. The present study was designed to determine by quantitative histochemistry whether the influx of neutrophils through the nasal respiratory epithelium would induce significant quantitative changes in the amount of intraepithelially stored mucosubstance. F344/N rats were intranasally instilled with endotoxin to elicit a transient influx of neutrophils into the nasal epithelium. Peak intraepithelial infiltration of neutrophils was evident 6 hours after instillation. There was a concurrent quantitative decrease in stored epithelial mucosubstance at the same time after instillation. Amounts of epithelial mucosubstance returned to that measured prior to neutrophil infiltration by 24 hours after instillation, when intraepithelial neutrophils were diminishing. Rats in which circulating neutrophils were sequestered in the lungs and prevented from migrating into endotoxin-exposed nasal epithelium had no change in the quantity of stored mucosubstance 6 hours after instillation. Therefore, it is concluded that a transepithelial migration of neutrophils elicits a transient depletion of stored mucosubstances in the nasal respiratory epithelium. Whether this is due to the release of secretagogues from the migrating leukocytes or another neutrophil-related method of stimulating mucous secretion is not known.     

Glycoconjugate histochemistry of bovine Brunner glands

The principal aims of this study have been to elucidate the nature of glycoconjugates produced by the two distinct parts of bovine Brunner glands, peripheral and central areas of lobules, and to investigate the presence of sialyl acid residues. Bovine duodenal tissues, embedded in paraffin wax, were investigated by means of both conventional histochemical methods (PAS, AB, HID) and biotinylated lectins (Con A, DBA, SBA, GS-I-B4, PNA, sWGA, GS-II, UEA-I, LPA, LFA). Conventional histochemical methods allowed us to accurately define two different areas: a central and a peripheral area. The central area, composed of secretory tubular tracts and the excretory duct, contained neutral glycoconjugates. The peripheral area was formed by both terminal alveolar and tubular secretory tracts and contained both neutral and acidic glycoconjugates, the latter partly carboxylated and partly sulfated. Lectin histochemistry confirmed differences highlighted by conventional histochemical methods and allowed us to characterise glycoprotein profiles of the preterminal and terminal tracts. The preterminal tracts and the excretory duct contained glycoconjugates with terminal D-Gal beta(1-3)GalNAc, alpha-D-Gal, alpha/beta-D-GalNAc, alpha/beta-D-GlcNAc, and internal beta(1-4) D-GlcNAc and alpha-Man residues. The terminal tracts were characterised by terminal alpha-L fucose, beta-D-GalNac, alpha/betaD-GlcNAc, alpha-D-Gal, alpha-D-GalNAc, and sialic acid residues. Internal beta(1-4) D-GlcNAc and alpha-Man residues were also identified. Finally, secretion of bovine Brunner glands is characterised by both O-linked and N-linked glycoproteins: cells located in the preterminal tracts and in the excretory duct produce mainly O-linked glycoproteins while cells located in the terminal tracts produce N-linked glycoproteins.     

The detection of Epstein-Barr virus in the lesions of salivary glands.

Epstein-Barr virus (EBV) is known in association with lymphoid and epithelial lesion. Because the salivary gland is an organ close to the oropharynx, it has a higher incidence of EBV infection and is a possible route of EBV infection. Formalin-fixed, paraffin embedded tissue sections of 87 cases of salivary gland diseases were used for the study of EBV with PCR, in situ PCR for EBNA-1 (EBV nuclear antigen-1), and immunohistochemistry for LMP-1 (latent membrane protein-1). EBV was detected in 12 cases (13.8%): 7 of nonspecific chronic sialadenitis (21.2%), 4 of Warthin's tumors (30.8%), and one lymphoepithelial carcinoma. EBNA-1 was negative in all the other lesions. EBV DNA was detected in the nucleus of epithelial cells and the surrounding lymphocytes. LMP-1 positivity was found in the cytoplasm of epithelial cells. The results of the present study showed that EBV is implicated in some of the inflammatory and neoplastic lesions of the salivary gland in which the lymphocytes are abundant. However, the pathogenesis and mechanism of immortalization and tumorigenesis of the epithelial cells in the salivary glands remain to be determined.     

Carbohydrate histochemistry of rat respiratory glands

Cytochemical methods applied to examination of rat respiratory tract glands have revealed diversity of secretory complex carbohydrates. With the Alcian blue-periodic acid Schiff (AB-PAS) and the high iron diamine (HID) techniques at the light microscopic level, certain patterns of glycoprotein content were noted at various levels of the respiratory tract. Serous tubules and demilunes found in abundance in laryngeal and tracheal glands contained neutral glycoprotein. Mucous tubules found in abundance in epiglottal and laryngeal glands and in lesser number in tracheal glands most often produced sulfated glycoprotein. However, mucous tubules in epiglottal and tracheal glands contained a few cells with sialylated glycoprotein, and mucous tubules in some areas in laryngeal glands contained mainly cells producing sialylated glycoprotein. Mucous ducts found in abundance in lower laryngeal and tracheal glands formed mainly sialylated glycoprotein and contained infrequent cells with sulfated glycoprotein. The type of glycoprotein found in each cell type by light microscopy was confirmed at the ultrastructural level by the periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP), dialyzed iron (DI) and high iron diamine (HID) methods. Serous cell granules displayed light reactivity with the PA-TCH-SP method and no DI or HID affinity and were judged to contain sparse neutral glycoprotein. Serous granules disclosed negative central foci with the PA-TCH-SP method. Granules of most mucous tubule cells stained strongly with the PA-TCH-SP and HID procedures and contained abundant sulfated glycoprotein. Occasional mucous tubules stained with the PA-TCH-SP but not with the HID method and apparently corresponded with cells judged to form sialylated glycoprotein from their blue staining with the HID-AB sequence. Two zones within individual granules in some cells revealed different HID staining intensity and appeared to differ in the amount or kind of sulfated glycoprotein they contained. Some cells exhibited granule heterogeneity containing both HID-positive and unstained granules. Spherical cores present in granules of mucous tubules below the upper laryngeal level occasionally appeared bizonal and invariably lacked reactivity demonstrative of complex carbohydrate. Mucous duct cell granules stained heavily with the PA-TCH-SP and DI methods and reacted infrequently with the HID procedure and were considered generally to contain sialylated glycoprotein, and occasionally to form sulfated glycoprotein. The three carbohydrate stains distinguished a heavily and a moderately reactive zone in the cortex outside the monophasic or biphasic, carbohydrate-free cores in granules of some mucous duct cells.     

Tumour-like lesions of the salivary glands. The new WHO classification.

Tumour-like lesions must be distinguished from true tumours of the salivary glands. In the new WHO classification of salivary gland tumours seven entities were considered: sialadenosis, oncocytosis (diffuse oncocytosis and focal adenomatous oncocytic hyperplasia), necrotizing sialometaplasia (salivary gland infarction), benign lymphoepithelial lesion (chronic myoepithelial sialadenitis), salivary duct cysts (mucoceles of the minor salivary glands of extravasation or retention type, cysts of the major salivary glands, ranula and dysgenetic polycystic disease of the parotid gland), chronic sclerosing sialadenitis of the submandibular gland (Küttner tumour), and cystic lymphoid hyperplasia in AIDS. The main topics of clinical data and pathohistology were described and documented by the results of the Salivary Gland Register in Hamburg (1965-1989).     

Papillary tumours of the minor salivary glands.

The clinical and histological features of oncocytic adenomatous hyperplasia, papillary adenoma, and papillary adenocarcinoma of the oral cavity are described, and the literature is reviewed. Histological features which may be of value in distinguishing between benign and malignant variants are described, and in view of the slow growth rate of most of these tumours, the importance of long-term follow-up is stressed.     

Lectin histochemistry of the canine anal glands

The distribution and selectivity of complex carbohydrates in the canine anal glands were studied by means of lectin histochemistry, using PO-labeled lectins. The secretory epithelium of the anal glands and the excretory duct system exhibited large amounts of mainly neutral glycoproteins with various terminal sugars (alpha-D-mannose, beta-N-acetyl-D-glucosamine, alpha-N-acetyl-D-galactosamine, alpha-D-galactose, alpha-L-fucose, N-acetyl-neuraminic acid). Distinctly prominent in the secretion were alpha-L-fucose residues. This relatively hydrophobic sugar may in particular modify or control the viscoelastic properties of the anal gland mucus, so that a stable mucous coat of the rather dry faeces can be formed. In addition, it was obvious that the major part of the excretory duct system is also involved in secretion production, and that the essential function of the saccular dilatations of the excretory ducts is to ensure secretion maturation.