A MORPHOLOGIC STUDY OF A CARCINOGENIC PROCEDURE IN THE HAMSTER SUBMANDIBULAR GLAND.
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Innervation of the lacrimal gland of MRL/Mp-Fas-lpr/lpr (MRL/lpr), a murine model for Sjögren's syndrome, is unaltered with the onset or progression of the lymphocytic infiltration. To determine whether lacrimal and submandibular gland cells are able to respond to external stimuli, acini were prepared from MRL/lpr (diseased) and MRL/Mp-+/+ (MRL/+, control) mice at 4, 8, and 12 weeks of age and loaded with the fluorescent dye fura-2 to monitor changes in the intracellular Ca2+ concentration ([Ca2+]i) in response to cholinergic and alpha1-adrenergic stimulation, two major stimuli of lacrimal gland protein secretion. Cholinergic-induced [Ca2+]i increase was up-regulated 3- and 4-fold in lacrimal gland acini isolated from 8- and 12-week-old MRL/lpr mice, respectively, compared to 4-week-old animals, but was not up-regulated in age-matched MRL/+ control mice. Similarly, alpha1-adrenergic-induced [Ca2+]i increase was up-regulated 7- and 12-fold in acini isolated from 8- and 12-week-old MRL/lpr mice, respectively, compared to 4-week-old animals, but was not up-regulated in MRL/+ mice. Cholinergic-induced [Ca2+]i increase in submandibular gland acini of MRL/lpr and MRL/+ mice was the same at all ages. In contrast, alpha1-adrenergic-induced [Ca2+]i increase was up-regulated 3-fold in acini from 12-week-old MRL/lpr mice, compared to 4-week-old mice, but was not up-regulated in age-matched MRL/+ mice. We conclude that the Ca2+ signaling portion of cholinergic and alpha1-adrenergic pathway in the lacrimal gland and the Ca2+ signaling portion of alpha1-adrenergic pathway in the submandibular gland is up-regulated with the onset and progression of the lymphocytic infiltration in the MRL/lpr murine model of Sjögren's syndrome.
We have investigated by immunochemistry the distribution of H Type 3/4 chains of the ABO histo-blood group system in human submandibular gland using a monoclonal anti-H MBr1 antibody specific for H Type 3/4 chains, and have found the expression of H Type 3/4 chains was mainly in the serous cells. Serous cells from secretors were stained by MBr1 but not by anti-A and anti-B antibodies, whereas serous cells from nonsecretors exhibited a negative reaction with MBr1. Mucous cells were not stained by MBr1. Only a few striated duct cells showed a weak reaction with anti-H MBr1. These results suggested that the H Type 3/4 chains were distributed predominantly in the serous cells of the human submandibular gland and that secretor Type alpha(1,2)fucosyltransferase (Se enzyme) controlled the synthesis of H Type 3/4 chains in vivo. Saliva also contained H Type 3/4 chains, which were controlled by the secretor gene (FUT2). The differences in the distributions of H Type 1, H Type 2, and H Type 3/4 chains of the ABO histo blood group system in the submandibular gland are discussed.
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The organization and fine structure of granular convoluted tubule cells (GCT) from male mouse submandibular glands have been examined in controls and in animals injected with adrenergic and cholinergic secretagogues. Control submandibular glands exhibited a single population of GCT cells with numerous homogeneous granules filling the apical two-thirds of the cytoplasm. A zone of transition cells, exhibiting characteristics of both GCT and striated duct cells, was found between the agranular intercalated duct and GCT segments. These transition cells possessed apical granules of variable size as well as prominent basal striations. Dramatic changes in the morphology of GCT cells followed administration of the alpha-adrenergic agent, phenylephrine. The extensive degranulation involved formation of "secretory pools" of fused granules and release of secretory material into the lumen. The appearance of numerous smooth vesicles near luminal membranes suggested extensive membrane retrieval. Intracellular membrane-limited aggregates of membrane fragments suggested that much of the retrieved membrane was destined for degradation. Rough endoplasmic reticulum was highly dilated but there was no indication of increased size or activity of the Golgi complex. Ultrastructural evidence indicated that the secretory responses to isoproterenol, a beta-adrenergic agent, and to pilocarpine, a cholinergic agent, were much more modest, but it is clear that some secretory response to these agents does occur. The other cell types of the duct and tubule system did not exhibit comparable morphological changes in response to the agents used.
A 34-year-old Japanese male had pain radiating from his right mandibular body to the temporal region. Computerized tomography was undertaken to examine his cerebral status. It eventually revealed the absence of the right submandibular gland, although the left submandibular gland was present. The corresponding space was occupied by a lymph node. Furthermore, sialography showed the existence of Wharton's duct only. The literature on this rare occurrence is reviewed and the significance to the patient discussed.
Cystic fibrosis (CF) and heterozygote sera stimulate a significant K+ efflux from rat submandibular gland fragments in the presence of 1 mM ouabain. This sensitive parameter can be maximally stimulated by as little as 0.5% CF serum and is inhibited by the calcium channel blocker D600 and EGTA. Specific receptor blockers propranolol, phenoxybenzamine or atropine do not inhibit the CF serum-stimulated K+ efflux and agonists do not supramaximally stimulate K+ efflux when added with serum. CF serum-induced K+ efflux did not result in the leakage of lactic dehydrogenase into the bathing media nor did it mimic the action of the calcium ionophore A23187 when added in the presence of D600. In addition, ultrafiltrates of CF serum (less than 10,000 daltons) also stimulated K+ efflux from rat submandibular gland tissue fragments.
The differences in susceptibility of animals to the lethal factor extracted from the mouse submandibular gland and magnitude of its lethality were compared among various species, strains, ages, and sex of mice. Comparisons of LD50 values computed by an IBM 360/System computer using a programmed probit analysis yielded the following significant results. The lethal factor of adult male mice was lethal to all species and strains of animals tested. Strain differences were observed in five inbred strains of mice, and varying degrees of resistance against the lethal factor were demonstrated. The lethality was strongest in the submandibular gland of our subline BALB/c mice, and the highest susceptibility to the lethal factor was demonstrated by female C57BL mice. This factor was found to be lethal not only to mice but also to other species of animals, Mongolian gerbils being most susceptible and New Zealand rabbits next.
Androgen-dependent sexual differences in the granular convoluted tubules of mouse and rat submandibular glands (SMG) have been extensively reported. We studied two major androgen-dependent mRNAs of the rat SMG encoding proteins named SMR1 and SMR2. To determine which cell type in the SMG is responsible for synthesis of these mRNAs, we performed in situ hybridization with digoxigenin-labeled RNA probes coupled with alkaline phosphatase detection. We show that SMR1 and SMR2 mRNAs are synthesized in the acinar cells of the SMG. A clear difference in SMR1 and SMR2 mRNA levels in male and female is demonstrated. During the course of this study we also confirmed the acinar localization of mRNAs encoding the glutamine/glutamic acid-rich proteins (GRP) of rat SMG. Our data are the first clear evidence of androgen-dependent sexual differences in acinar cells of rat submandibular gland.
Oncocytic carcinoma arising in the submandibular gland is a very rare tumor that has only previously been reported in nine cases. This paper describes an additional case of oncocytic carcinoma in the right submandibular gland. The patient was a 55-year-old Japanese male who was presented with a 3 cm right submandibular mass. Both radical resection of the tumor and right supraomohyoid neck dissection were performed. Histologically, the tumor cells exhibited an abundant eosinophilic cytoplasm, which appeared to be finely granular, and invaded the surrounding tissues. In addition, perineural invasion was also observed. Electron microscopy demonstrated the presence of an abundance mitochondria in the cytoplasm of the tumor cells. However, since the fine structure of cytoplasm was destroyed by fixation and embedding of the tissue for the light microscopy, the cytoplasm of the tumor could not be observed clearly. Immunohistochemically, anti-mitochondrial antibody positivity was evident in the cytoplasm of the tumor cells. Consequently, we diagnosed the mass as oncocytic carcinoma. Usually, electron microscopy is necessary to diagnose oncocytic lesions, but the paraffin-embedded tissue was not suitable for electron microscopy. Immunohistochemistry using an anti-mitochondrial antibody was found to be useful and helpful for the diagnosis of oncocytic lesions.
The embryonic development of the salivary gland in the mouse was studied by scanning electron microscope (SEM). The submandibular morphogenesis was found to take place within its associated mesenchymal tissue. This stromal mesenchymal element has prevented us from observing three-dimensional details of the branching morphogenesis by SEM. In the present study, we applied a modified Evan's enzymatic digestion method to the embryonic submandibular gland. Consequently, we obtained important information about the morphogenetic events for the branching development of the mouse submandibular gland, demonstrating that a pit and shallow clefts are formed on the lateral aspect of the spherical end bud. This pit and cleft formation likely represents the initial morphogenetic movement of the epithelium that establishes primary branchings. Furthermore, SEM observation of the basal surface of the embryonic epithelial cells provided us views of the developmental change of cell projections probably involving epithelial-mesenchymal contacts.
1. Acetylcholine-mediated (ACh-mediated) secretion of fluid and protein from rat submandibular glands was enhanced by intravenous injection of vasoactive intestinal peptide (VIP) and of secretin but not of peptide histidine isoleucine (PHI) or gastric inhibitory peptide (GIP). 2. When VIP and ACh were administered together, the enhancement of fluid secretion was inhibited by pretreatment with atropine or 4-DAMP and the enhancement of protein secretion was inhibited by pretreatment with atropine or phentolamine. 3. The enhancement of the ACh-induced secretion of fluid by secretin was strongly inhibited by pretreatment with atropine, and it was weakly inhibited by pretreatment with phentolamine or haloperidol. 4. These results suggest that the synergistic effects of VIP, PHI, secretin and GIP on the ACh-mediated secretion of fluid and protein from the rat submandibular gland do not reflect the extent of the structural homology of each peptide to VIP.
The effect of angiotensin II (Ang II) was studied on blood flow in the submandibular gland and tongue in male rats. Blood flow changes were determined with laser Doppler flowmetry and Ang II was infused into the common carotid artery before and after i.v. doses (18 nmol kg-1) of the angiotensin II antagonist saralasin. Angiotensin II (10-60 pmol min-1) dose-dependently increased blood pressure and tongue blood flow, whereas glandular blood flow decreased at all of the doses used. After saralasin administration the angiotensin II effects on blood pressure, tongue and glandular blood flow were significantly diminished (glandular blood flow reduction was diminished from 29%-3%, P less than 0.005, n = 9). However, the responsiveness of these 3 parameters to local infusions with noradrenaline (0.75-3.0 pmol min-1) was unaffected by saralasin. The dose of saralasin used in the present study did not affect any of the parameters on it's own. Our results show that vascular receptors sensitive to angiotensin II operate in the submandibular gland but not in the tongue.
A new, third type of secretory cell was found in the acini of the submandibular gland in rat. In paraffin sections stained with hematoxylin-eosin or reacted with periodic acid-Schiff, acini containing the third type of secretory cells were found as a mass of darkly stained secretory endpieces at the periphery of the lobule. In semi-thin sections stained with toluidine blue, these cells showed numerous dense secretory granules in their cytoplasm. Some acini consisted entirely of these cells, whereas other acini consisted of an admixture of such cells and typical seromucous cells. Acini containing the third type of secretory cell tended to form clusters. Electron microscopically, the cells had well-developed rough endoplasmic reticulum and Golgi apparatus. The secretory granules showed a wide range of variation in substructure, even within the same cell. Well-developed intercellular interdigitation and intercellular canaliculi also were observed between adjacent third type of secretory cells. Although little is known about the biological significance of these cells and the properties of their secretory granules, the present study shows that the rat submandibular gland possesses three types of secretory cells in their secretory endpieces.
BACKGROUND AND PURPOSE: The submandibular glands produce most of the unstimulated saliva output and are the key in prevention of radiation-related xerostomia. We investigated whether sparing of the submandibular function is feasible with intensity modulated radiotherapy (IMRT). PATIENTS AND METHODS: Thirty-six patients diagnosed with head and neck cancer were treated with IMRT and had at least one parotid gland excluded from the planning target volume. In a subset, of these patients (n=18) where the risk of cancer recurrence in the contralateral submandibular region was judged low, the contralateral submandibular gland was spared from full-dose irradiation. The total unstimulated and stimulated salivary flow rates and adverse effects were monitored. RESULTS: Twelve months following IMRT mean unstimulated saliva flow was 60% of the baseline value among patients who had one submandibular gland spared and 25% among those who did not (P=0.006). Patients whose contralateral submandibular was spared reported less grade two or three xerostomia (4 vs. 11; P=0.018), and used less saliva substitutes. No cancer recurrences were detected at the vicinity of the spared glands during a median follow-up time of 31 months. CONCLUSIONS: Submandibular gland sparing with IMRT is safe in selected patients treated for head and neck cancer. It is effective in prevention of radiation-associated xerostomia.
Cyclic AMP response element-binding protein (CREB) is a 43-kDa polypeptide that binds a cAMP response element located at the 5' promoter region of cAMP regulatory genes. The spatial and temporal distribution of CREB in the postnatal development of the rat submandibular gland was investigated using immunohistochemistry with a specific antibody. At birth, cells of the terminal tubules and ducts in the submandibular gland showed a nuclear CREB immunoreactivity of moderate intensity. At 1-2 weeks after birth, an intense CREB immunoreactivity was localized primarily to acinar cells. When the beta-adrenergic agonist isoproterenol was administered to 2-week-old rats, a twofold transient increase in the number of immunoreactive acinar cells was induced. Beginning 3 weeks after birth, CREB immunoreactivity shifted from acini to the duct system and showed a clear localization in the cells of the intercalated ducts and distal portions of striated ducts, where the granular convoluted tubule develops after 4 weeks. Immunopositive materials were localized exclusively in the nuclei of both acinar and ductal immunoreactive cells. After the development of the granular convoluted tubules, CREB immunoreactivity was absent in the tubule cells and was gradually reduced in intensity over the entire gland. In order to examine a hypothesis that CREB is involved in the initial differentiation of the granular convoluted tubular cells, testosterone was administered to hypophysectomized adult rats. Whereas the tubular cells of hypophysectomized rats showed a complete regression, and no CREB immunoreactivity was found in any acinar or duct cells, administration of testosterone for a few days induced an intense CREB immunoreactivity in the nuclei of duct cells, followed by their differentiation into the granular convoluted tubular cells. These results suggested that CREB is involved not only in the growth and differentiation of acinar cells that are regulated by beta-adrenergic nerves but also in those of the duct system, and especially in the androgen-regulated differentiation of the granular convoluted tubular cells, during the post-natal development of the rat submandibular gland.
Irradiation of rabbit submandibular glands with a single absorbed dose of 15 Gy caused tissue damage which persisted 4 and 10 months later. The injuries were studied by histology, measurement of gland weights and histomorphometry. Reduction of gland weight due to hypoplasia and missed weight gain were seen and the proportions of the three major intralobular compartments of the glands were altered being dependent on the interval between radiation exposure and observation time. The size of the lobules was reduced and extralobular fibrosis in the hilar region increased. The seromucous acini were partly atrophied, with successively changed architecture and reduced size of the granules. The serous tubules showed pronounced reduction of the granules at 4 months and a remarkable adenomatous regeneration at 10 months post irradiation. The striated ducts were almost unaffected during the observation time. Arteriolar changes were slight to moderate, and there was scarcely any capillary damage. The numbers of intra- and extralobular plasma cells were increased.