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Renin was found in the submandibular glands of male Quackenbush mice in concentrations higher than has been reported for any tissue of any strain or species. However, no renin-like activity could e detected in glands from male and female Wistar rats using either pH 5.8 or 7.4 for assay and a radioimmunoassay specific for renin's reaction product, angiotensin I. Rabbit submandibular glands contained renin.
The localization of endogenous peroxidase was studied in human parotid and submandibular glands using the medium of Strum & Karnovsky either at pH 7 or at pH 8.3, after a short fixation of the tissues with a low concentration of glutaraldehyde. At pH 7 reaction product was found in seromucous cells of both glands in the cisternae of the rough endoplasmic reticulum, in the elements of the Golgi apparatus, and in secretory products. However, while in the parotid gland all secretory granules showed peroxidase activity, in the submandibular gland some of the granules were left unstained. At pH 8.3 the pattern of reactivity was practically unchanged in the submandibular gland, whereas the amount of precipitate noticeable in the secretory granules of the parotid gland was greatly reduced. The method of Novikoff et al. for catalase revealed the presence of a number of small bodies having in the characteristics of peroxisomes. Acid phosphatase was not demonstrable in the secretory granules of either parotid or submandibular glands. The lead precipitate indicating enzyme activity was observed only in lysosomes and, occasionally, in the elements of the Golgi apparatus of some sermucous cells.
Early morphogenesis of mouse submandibular glands begins on late day 11 of fetal development when the epithelium begins to bud from the surrounding mandibular mesenchyme. Using total RNA collected from fetal BALB/c submandibular glands, steady-state levels of mRNA expression for extracellular matrix molecules were measured using quantitative competitive reverse transcription-polymerase chain reaction (RT-PCR). By comparing the PCR amplification products of both the cellular mRNA and a synthetic template, pMATRIX, it was possible to measure the direct expression of collagens alpha2(I), alpha1(III), alpha1(IV), fibronectin, laminin B2, elastin and lysyl oxidase genes. There was an observed trend for an increasing concentration of collagen alpha2(I), collagen alpha1(III) and lysyl oxidase mRNA molecules per cell on day 16 of development. The relative abundance of elastin mRNA was detectable only on day 16. Fibronectin and laminin B2 were more constitutively present but had their highest copy number per cell on day 16. The presence of extracellular-matrix protein was confirmed by immunohistochemistry using day-16 fetal glands and adult glands. With the construction of the pMATRIX supertemplate and the advent of quantitative, competitive RT-PCR technology, it has been possible to measure small changes in the steady-state concentrations for extracellular-matrix mRNA during salivary gland development.
Morphological changes in submandibular glands of female mice following ovariectomy were studied morphometrically by light microscopy and ultrastructurally by electron microscopy. The X zone of the adrenal gland was examined in order to assess possible changes that might be expected to occur after ovariectomy. In submandibular glands, 1 to 4 weeks after ovariectomy, no changes were observed in percentages of the acinar, intercalated duct, and granular convoluted tubular areas occupying photomicrographs. However, an increase in the granular content of both intercalated duct and granular convoluted tubular cells was recognized. By contrast, the glandular picture 4 months after ovariectomy changed remarkably, resembling that of the male mouse both morphometrically and in terms of fine structure. In the adrenal cortex of control female mice, the X zone became thinner with aging. As compared with this, the X zone of ovariectomized mice at any time after the operation was thicker than that of controls. These observations suggest that the absence of ovarian hormones in the ovariectomized mouse may lead to prolonged functioning of X zone cells, which in turn may cause masculinization of the submandibular gland.
We have previously demonstrated that the rat submandibular gland releases immunoreactive kallikrein into the circulation. To study the role of the autonomic nervous system in this release, submandibular gland blood flow and kallikrein concentration in peripheral arterial and venous blood from the gland were measured and secretion rates calculated before and after parasympathetic and sympathetic nerve stimulation (8V, 2 msec, 10 Hz) for 1 minute. Immunoreactive kallikrein in plasma was measured by radioimmunoassay, and timed collections of venous outflow were used to measure blood flow. During basal conditions, the unstimulated submandibular gland of the rat released immunoreactive kallikrein into blood at the rate of 0.92 +/- 0.07 ng/min. Parasympathetic stimulation increased blood flow 4-fold (before, 68.5 +/- 8.3 microliters/min; after, 253.5 +/- 76.2; P less than 0.05) without significantly changing immunoreactive kallikrein secretion rate. Sympathetic stimulation produced an 11-fold increase in blood flow (before, 64.9 +/- 9.3 microliters/min; after, 709.6 +/- 97.5; P less than 0.05) and a 57-fold increase in immunoreactive kallikrein secretion rate from the gland (before, 1.05 +/- 0.25 ng/min; after, 59.8 +/- 18.6; P less than 0.05). Sympathetic stimulation also produced a 4-fold increase in the concentration of immunoreactive glandular kallikrein in arterial plasma (before, 15.2 +/- 1.1 ng/ml; after, 56.2 +/- 12.9; P less than 0.05). Pretreatment with phentolamine (1 mg/kg) or prazosin (0.2 mg/kg) blocked the increase in kallikrein secretion rate produced by sympathetic stimulation. These results indicate that the sympathetic nervous system, through activation of alpha 1-adrenoreceptors, controls kallikrein secretion from the submandibular gland into the circulation. Released kallikrein may be responsible for the reactive vasodilation observed in the rat submandibular gland after sympathetic stimulation.
Fragments of rat submandibular gland (organoids) which maintained the topological organization of the parent tissue were cultured in a three-dimensional collagen gel matrix for up to 30 days. At 48 h, vigorous peripheral outgrowth had occurred around each organoid. This was accompanied by central necrosis and the bridging of adjacent organoids. By day 5, large cyst-like spaces occupied the centre of many organoids. Bromodeoxyuridine labelling indicated that a considerable proportion of the lining cells were proliferating. Organoid growth peaked at between 5 and 10 days. Thereafter, the number of viable colonies and proliferating cells declined. Addition of isoproterenol after 24 h culture resulted in marked morphological alterations, with earlier and more prolific outgrowth and a greater tendency for organoids to flatten and grow out over the surface of the gel with squamous differentiation. Ultrastructurally, nuclear and cytoplasmic features of isoproterenol-treated and untreated cultures were similar. The secretory granules and extensive rough endoplasmic reticulum of terminal tubule cells, evident in organoids immediately after isolation, were infrequent after 24 h and absent by 48 h. Similar alterations occurred in the few acinar cells, so by 5 days the cultures were composed entirely of a uniform population of primitive, dedifferentiated cells. Further uses of this culture systems will include the study of diseases and disorders of the salivary glands as well as normal growth and differentiation pathways.
The structure of normal human submandibular glands has been studied with the electron microscope. Secretory cells are arranged around a central lumen, and are surrounded by numerous myoepithelial cells, showing tapering process. Intercalated and striated ducts follow secretory units. Striated ducts' cells are characterized by extensive infoldings of the basal plasma membrane, among which numerous mitochondria are aligned. Furthermore, the Authors examine the submandibular gland's innervation.
The innervation of the submandibular glands of the mouse by the autonomic nervous system and the influence of receptor-selective mimetics of the neurotransmitter substances on these glands have been studied with histological techniques. The mimetics were administered either via an intraperitoneal injection or via the perfused blood vessels. The acini and granular convoluted tubules were surrounded by both an adrenergic and a cholinergic plexus. Both types of transmitter mimetics were able to stimulate the exocytotic secretion from the acinar cells either via the beta-adrenoceptor or via the cholinergic muscarinic receptor within 45 min of perfusion. Strongest effect was observed after stimulation of the former receptor. Aso 90 min after an intraperitoneal injection it was observed that both isoprenaline and pilocarpine stimulated the granular release from the acinar cells. On the other hand, the granular secretion from the convoluted tubules was predominantly stimulated by adrenergic agonists though these cells, like the acinar cells, received a dual innervation. In contrast to the acinar cells the secretory process in the tubular cells was stimulated via both the alpha- and beta-adrenoceptor. Stimulation of the alpha-adrenoceptor induced the most distinct effect, which found expression in an explosive granular secretion within 15 min of perfusion, during which process the luminal plasma membranes seemed to be disrupted. The effect of isoprenaline was obvious only after 45 min of perfusion. However, 90 min after an intraperitoneal injection of either isoprenaline or phenylephrine the convoluted tubules were almost completely depleted of granules. Stimulation of the cholinergic muscarinic receptor by pilocarpine resulted only in a slight secretory effect, both in vivo and during perfusion.
Androgens have profound effects on the murine submandibular gland. Our objective was to determine the nature and extent of androgen control of gene expression in the submandibular gland, and to explore the degree to which this might account for known sex differences. Orchiectomized male BALB/c mice were treated with placebo- or testosterone-containing hormone pellets for 14 days. Glands were collected, and total RNA was isolated. Samples were analyzed for differentially expressed mRNAs by CodeLink microarrays, and the data were evaluated with GeneSifter. Androgens significantly (p < 0.05) influenced the expression of over 1300 genes, and many (n = 366) of the genes differentially regulated by androgen treatment were also differentially expressed in males compared with the females in our previous study. These findings support our hypotheses that testosterone extensively influences gene expression in the male submandibular gland, and that many of the sex differences are due to androgens.
Submandibular glands of rats injected with NaF solution (10 mg F-/kg body weight) were analysed for glycogen content and phosphorylase activity after various time intervals. In contrast to what has been reported for the liver, sodium fluoride caused increased glycogen content. Phosphorylase (a and total) activity was not affected, suggesting a different mechanism of action of F- in the submandibular gland. In vivo experiments demonstrated stimulation of glycogenesis.
Androgens exert significant effects on the murine submandibular gland. Our objective in this study was to determine the nature and extent of testosterone regulation of gene expression in the female submandibular gland, and to explore the degree to which this control is the same as in male glands. Ovariectomized female BALB/c mice were treated with placebo- or testosterone-containing hormone pellets for 14 d. Glands were collected and total RNA was isolated. Samples were analyzed for differential expression of mRNA using CodeLink microarrays, and the data were evaluated using genesifter. Testosterone significantly influenced the expression of over 500 genes, and while many (n = 214) of the genes were similarly differentially expressed in androgen-treated males, there were also many that were unique. These findings support our hypotheses that testosterone extensively influences gene expression in the female submandibular gland, and that the nature of this influence is variable between sexes.
PURPOSE: In this study, we designed an animal experiment in which we transferred a part of the autologous submandibular gland without performing a microvascular anastomosis. We studied histological changes and functional effects in the transfer glands. METHOD: Thirty male adult Sprague-Dawley rats were divided into three groups. In each animal of the three groups, the right eye was the control eye and the left eye the experimental eye. Surgical removal of the extraorbital lacrimal gland from the control eyes was performed to create a condition simulating keratoconjunctivitis sicca. In the experimental eyes of group 1, in addition to the removal of the extraorbital lacrimal gland, a part of the autologous submandibular gland was transferred to the orbit and fixed to the intraorbital lacrimal gland. In the experimental eyes of group 2, in addition to the removal of the extraorbital lacrimal gland, an aseptic silicon rubber was transferred to the orbit and fixed to the intraorbital lacrimal gland. In the experimental eyes of group 3, there was no removal of the extraorbital lacrimal gland but instead a sham operation was performed. The histological changes and innervation pattern in the transferred submandibular gland of group 1 were observed. Tear secretion of each group was measured to study the functional effect. RESULTS: Three months after the transplantation, the transferred submandibular glands were similar to the unoperated submandibular glands both in histology and innervation pattern. In group 1, the tear secretion in the experimental eyes was significantly greater than that of the control eyes at 2 and 3 months following transfer. In group 2, no significant difference was noted between the experimental eyes and control eyes. In group 3, the difference in tear secretion between the experimental eyes and control eyes was significant. CONCLUSION: The result of this study revealed that although the procedure did not involve vascular anastomosis, the transfer gland showed a normal histological appearance and good reinnervation, even 3 months after the transfer. These transferred submandibular glands continued to secrete tears. This secretion continued to increase up until the end of the experimental period.
OBJECTIVE: To examine the feasibility of endoscopic resection of the submandibular gland in a porcine model. STUDY DESIGN: Experimental, nonrandomized prospective study. METHODS: Twelve endoscopic submandibular gland resections were performed on seven Yorkshire adult pigs using a combination of balloon dissection and low-pressure CO2 insufflation. The operative time, blood loss, blood pressure, oxygen saturation, temperature, arterial blood gas values, and weight of the glands were measured. RESULTS: All 12 submandibular gland resections were successfully performed endoscopically, and no conversions to open resection were necessary. The procedures lasted 42 to 140 minutes (median duration, 59 min). The median estimated blood loss was 15 mL. The submandibular glands weighed 13.3 +/- 1.5 g. The arterial blood pH varied from a decrease of 0.08 to an increase of 0.09 units from the beginning to the end of the operation. Similarly, the arterial CO2 pressure at the end of the case varied from a decrease of 15.8 to an increase of 16.2 mm Hg from the starting value. The presence of normal glandular architecture and lack of trauma or thermal injury were confirmed histologically. There were no cases of pneumothorax or air embolism, and no animals had to be killed. In one animal, a modest amount of subcutaneous emphysema could be appreciated, which was confined to the area over the operative pocket. CONCLUSION: Endoscopic resection of the submandibular gland is possible by combining balloon dissection with low-pressure CO2 insufflation, thereby avoiding complications of high-pressure insufflation such as pneumothorax and air embolism.
Renin in the female mouse submandibular gland (SMG) is known to increase in response to thyroid hormone. In the present study a 500 base-pair renin cDNA was used to quantify renin mRNA, the product of transcription of the Ren-2 gene, in the female mouse SMG in response to thyroid hormone to assess more directly the nature of stimulation of renin biosynthesis. After daily injection for 1 wk renin mRNA increased from control values of 36 +/- 3 SE ng/g tissue to 212 +/- 41 with triiodothyronine (T3; P less than 0.005) and to 217 +/- 33 with thyroxine (T4; P less than 0.005). Treatment of mice with propylthiouracil (PTU) decreased renin mRNA to 1.2 +/- 0.3 (P less than 0.005) and after subsequent injection of T3 for 1 wk renin mRNA increased to 289 +/- 35 ng/g tissue. The time course of the response to a single injection of thyroid hormone indicated a rapid response with significant increases in renin mRNA by 1 h, reaching values 3.5 +/- 0.4 times control (P less than 0.005) by 5 h. Such rapid effects are consistent with a direct nuclear action of thyroid hormone in stimulating transcription of the Ren-2 gene in mouse submandibular gland or in stabilization of nuclear precursor renin mRNA or both.
An oncocytic carcinoma of the submandibular gland diagnosed by fine-needle aspiration is reported. Cytologically, the tumor cells occurred singly, in three-dimensional clusters and in multilayered sheets. The cells had round-to-oval, centrally or eccentrically located nuclei with fine chromatin and prominent nucleoli. Many cells contained abundant granular cytoplasm and well-defined cell borders; however, several stripped nuclei with prominent nucleoli were also noted in the background. Follow-up histologic examination showed tumor cells arising from right submandibular gland and metastasizing to six of 14 cervical lymph nodes. Ultrastructural study demonstrated tumor cells packed with mitochondria in the cytoplasm. The patient was alive with no evidence of disease 6 months after the surgery.
1. The influence of hormones on the submandibular gland of rodents has attracted more attention since the observation of the sexual dimorphism of these organs. Androgens enhance both the development and the secretory activity of the gland. 2. In the present investigation we have studied the differences in wet weight, protein content, glandulain activity and morphometry of granular convoluted tubules of submandibular glands excised from control, castrated and antiandrogen-treated (RU 23908 or cyproterone acetate) male adult albino rats. 3. Castration and antiandrogenic treatment did not affect the wet weight or protein content of the organs. Castration or treatment with RU 23908, but not treatment with cyproterone acetate, decreased glandulain activity and the height of the secretory epithelium of granular ducts. 4. The morphology and glandulain activity of submandibular gland granular ducts do not seem to be related solely to plasma testosterone concentration. Different hormonal treatments are needed to identify other factors implicated in the phenomenon.
The submandibular glands of 6 human fetuses, 13.5-16 weeks old, were studied using light and electron microscopic techniques. The developing gland at this stage consisted of a bush-like network of terminal buds (primitive acini) and primary ducts surrounded by a loose mesenchyme. Both components had a lumen which was surrounded by 1 or 2 layers of epithelial cells. Those cells adjacent to the lumen were attached by desmosomes but lacked well developed terminal bars. The cells were separated by an intercellular space, into which projected numerous microvilli. The cytoplasm of the epithelial cells contained the usual organelles with some cells containing large accumulations of glycogen granules. Serous granules and the luminal contents were both strongly PAS and AB positive. The function of this secretory material, at this stage of human development, is unknown. No mucus-like granules were observed. The terminal buds and primary ducts were surrounded by a well developed basal lamina and contained a few elongated cells which appeared morphologically as developing myoepithelial cells. Morphologically the development of the human submandibular gland, at 13.5-16 weeks of age, is roughly equivalent ot the developmental stage of the gland seen in the newborn rat or mouse. By birth, the human submandibular gland would likely reach a mature state, because there would be ample time remaining, in a normal gestation, for the maturation process to be completed.
BACKGROUND: Xerostomia is a devastating complication of radiation therapy. Previous research has demonstrated that submandibular glands may be removed from the neck and transplanted using microvascular techniques, with good gland survival. However, microvascular transplantation and replantation has never been attempted on a composite tissue such as a salivary gland. OBJECTIVE: To evaluate the ability of a rabbit submandibular gland to undergo 2 successive microvascular transplantations. SUBJECTS AND DESIGN: Study rabbits underwent a midline neck incision with dissection of a submandibular gland to its arterial and venous pedicle. Microvascular techniques were then used to transplant the gland to the femoral system of the right groin. The incisions were reopened later under surgical conditions. The transferred gland was examined for survival and patency of its artery and vein. Healthy glands were dissected and transferred to a suitable artery and vein within the neck, where they were again reanastamosed using microvascular surgical techniques. After additional time, the gland was again examined for survival and pedicle patency, then removed and evaluated for histopathological evidence of survival. RESULTS: Surgical technique evolved during the course of this work to avoid encountered pitfalls. After refining the technique, we have determined that the rabbit submandibular gland is able to withstand successive microvascular transplantation and replantation with good likelihood of long-term survival, according to histopathological criteria. CONCLUSIONS: The rabbit submandibular gland is able to undergo microvascular transplantation and replantation with evidence of long-term survivability and preserved function. The body's natural response to surgery and tissue transplantation makes replantation a technical challenge; however, methods delineated herein alleviate many of the potential pitfalls. Extending these results to humans, patients who are to undergo radiation therapy could have a disease-free gland removed from the neck, transferred outside of the field of radiation, and then returned to the neck at the completion of radiation therapy. This may enable them to maintain salivary gland function and maintain oral cavity function and comfort.