Tlx1 regulates acinar and duct development in mouse salivary glands.

Tlx1 encodes a transcription factor expressed in several craniofacial structures of developing mice. The role of Tlx1 in salivary gland development was examined using morphological and immunohistochemical analyses of Tlx1 null mice. Tlx1 is expressed in submandibular and sublingual glands but not parotid glands of neonatal and adult male and female C57Bl/6J (Tlx1+/+ ) mice. TLX1 protein was localized to the nuclei of terminal tubule cells, developing duct cells and mesenchymal cells in neonatal submandibular and sublingual glands, and to nuclei of duct cells and connective tissue cells in adult glands. Occasionally, TLX1 was observed in nuclei of epithelial cells in or adjacent to the acini. Submandibular glands were smaller and sublingual glands were larger in size in mutant mice (Tlx1-/- ) compared to wild-type mice. Differentiation of terminal tubule and proacinar cells of neonatal Tlx1-/- submandibular glands was abnormal; expression of their characteristic products, submandibular gland protein C and parotid secretory protein, respectively, was reduced. At 3 weeks postnatally, terminal tubule cells at the acinar-intercalated duct junction were poorly developed or absent in Tlx1-/- mice. Granular convoluted ducts in adult mutant mice were decreased, and epidermal growth factor and nerve growth factor expression were reduced. Along with normal acinar cell proteins, adult acinar cells of Tlx1-/- mice continued to express neonatal proteins and expressed parotid proteins not normally present in submandibular glands. Sublingual gland mucous acinar and serous demilune cell differentiation were altered. Tlx1 is necessary for proper differentiation of submandibular and sublingual gland acinar cells, and granular convoluted ducts. The mechanism(s) underlying Tlx1 regulation of salivary gland development and differentiation remains unknown.

Differential immunohistochemical expression of type I collagen and matrix metalloproteinase 2 among major salivary glands of young and geriatric mice.

OBJECTIVE: This study aimed to demonstrate the immunohistochemical changes associated with MMP-2 and type 1 collagen separately for the first time in the major salivary glands (the parotid, submaxillary, and sublingual glands) that occur with aging in mice. MATERIAL AND METHODS: Fourteen Balb/c white mice (50-80 g) were used in this study. The animals were divided into two equal groups. Group I consisted of young animals (2-month-old) (n=7) and Group II consisted of older animals (18-month-old) (n=7). After routine histological follow-ups, Hematoxylin-eosin (H&E), Masson's Trichrome staining and immunohistochemical staining was performed for type I collagen and MMP-2. RESULTS: We observed that there were age-related decreases in the number of acinar cells, increase in eosinophilic zymogen granules in cells, collagen accumulation in fibrotic areas and dilatation in interlobular ducts. Also, while type I collagen and MMP-2 immunoreactivity were moderate in the salivary glands of the young mice, they were high in the salivary glands of the old mice (p=0.001). In the H-score assessment, MMP-2 immunoreactivity was lower at a significant level in young mice than in old mice (p=0.001). CONCLUSIONS: This study showed that anatomical, physiological and morphological abnormalities occur in all three major salivary glands as a natural consequence of aging.

Differential immunohistochemical expression of type I collagen and matrix metalloproteinase 2 among major salivary glands of young and geriatric mice

Abstract Objective This study aimed to demonstrate the immunohistochemical changes associated with MMP-2 and type 1 collagen separately for the first time in the major salivary glands (the parotid, submaxillary, and sublingual glands) that occur with aging in mice. Material and Methods Fourteen Balb/c white mice (50-80 g) were used in this study. The animals were divided into two equal groups. Group I consisted of young animals (2-month-old) (n=7) and Group II consisted of older animals (18-month-old) (n=7). After routine histological follow-ups, Hematoxylin-eosin (H&E), Masson's Trichrome staining and immunohistochemical staining was performed for type I collagen and MMP-2. Results We observed that there were age-related decreases in the number of acinar cells, increase in eosinophilic zymogen granules in cells, collagen accumulation in fibrotic areas and dilatation in interlobular ducts. Also, while type I collagen and MMP-2 immunoreactivity were moderate in the salivary glands of the young mice, they were high in the salivary glands of the old mice (p=0.001). In the H-score assessment, MMP-2 immunoreactivity was lower at a significant level in young mice than in old mice (p=0.001). Conclusions This study showed that anatomical, physiological and morphological abnormalities occur in all three major salivary glands as a natural consequence of aging.

Dopamine, vesicular transporters, and dopamine receptor expression in rat major salivary glands.

The localization of dopamine stores and the expression and localization of dopamine (DAT) and vesicular monoamine transporters (VMAT) type-1 and -2 and of dopamine D1-like and D2-like receptor subtypes were investigated in rat submandibular, sublingual, and parotid salivary glands by HPLC with electrochemical detection, as well as immunochemical and immunohistochemical techniques. Male Wistar rats of 2 mo of age were used. The highest dopamine levels were measured in the parotid gland, followed by the submandibular and sublingual glands. Western blot analysis revealed DAT, VMAT-1, VMAT-2, and dopamine receptors immunoreactivity in membrane preparations obtained from the three glands investigated. Immunostaining for dopamine and transporters was developed within striated ducts. Salivary glands processed for dopamine receptors immunohistochemistry developed an immunoreaction primarily in striated and excretory ducts. In the submandibular gland, acinar cells displayed strong immunoreactivity for the D2 receptor, while cells of the convoluted granular tubules were negative for both D1-like and D2-like receptors. Parotid glands acinar cells displayed the highest immunoreactivity for both D1 and D2 receptors compared with other salivary glands. The above localization of dopamine and dopaminergic markers investigated did not correspond closely with neuron-specific enolase (NSE) localization. This indicates that at least in part, catecholamine stores and dopaminergic markers are independent from glandular innervation. These findings suggest that rat major salivary glands express a dopaminergic system probably involved in salivary secretion. The stronger immunoreactivity for dopamine transporters and receptors in striated duct cells suggests that the dopaminergic system could regulate not only quality, but also volume and ionic concentration of saliva.

mRNA expression and localization of LPS-induced ß-defensin isoforms in rat salivary glands.

ß-defensins are small, cationic peptides with broad-spectrum antimicrobial activity that are produced by mucosal epithelia. However, little is known about the expression of ß-defensins in the major salivary glands. The purpose of this study was to characterize expression of rat ß-defensin-1 (RBD-1) and -2 (RBD-2) mRNA within the major salivary glands together with the effect of injection of intraductal lipopolysaccharide (LPS) on that expression. ß-defensin mRNA expression was quantitated by RT-PCR in salivary gland tissues and salivary acinar and striated duct cells collected by laser captured microdissection. RBD-1 and -2 were expressed in the parotid gland, the submandibular gland, and the sublingual gland. ß-defensins were expressed in both the acinar and striated duct cells of the major salivary glands. Intraductal injection of LPS increased expression of RBD-1 and -2 mRNA, which peaked at 12 hrs. These results suggest that salivary cells (acinar and striated duct cells) have the potential to produce ß-defensins.

The proteomes of human parotid and submandibular/sublingual gland salivas collected as the ductal secretions.

Saliva is a body fluid with important functions in oral and general health. A consortium of three research groups catalogued the proteins in human saliva collected as the ductal secretions: 1166 identifications--914 in parotid and 917 in submandibular/sublingual saliva--were made. The results showed that a high proportion of proteins that are found in plasma and/or tears are also present in saliva along with unique components. The proteins identified are involved in numerous molecular processes ranging from structural functions to enzymatic/catalytic activities. As expected, the majority mapped to the extracellular and secretory compartments. An immunoblot approach was used to validate the presence in saliva of a subset of the proteins identified by mass spectrometric approaches. These experiments focused on novel constituents and proteins for which the peptide evidence was relatively weak. Ultimately, information derived from the work reported here and related published studies can be used to translate blood-based clinical laboratory tests into a format that utilizes saliva. Additionally, a catalogue of the salivary proteome of healthy individuals allows future analyses of salivary samples from individuals with oral and systemic diseases, with the goal of identifying biomarkers with diagnostic and/or prognostic value for these conditions; another possibility is the discovery of therapeutic targets.

Localization of FGF-6 and FGFR-4 during prenatal and early postnatal development of the mouse sublingual gland.

A number of fibroblast growth factors (FGFs) are involved in regulatory mechanisms of the salivary gland development. However, the role of FGF-6 unique in myogenic cells has not been elucidated in the developing sublingual gland. In the present study, temporo-spatial expression of FGF-6 and its receptor (FGFR)-4, in conjunction with some related histo-chemical properties, were investigated in the sublingual gland of the prenatal and early postnatal mice. The earliest expression of both FGF-6 and FGFR-4 was detected in immature acinar cells at gestational day 17 (GD17). The staining intensity increased gradually and some acinar cells showed a distinct staining at postnatal day 0 (PD0). The immunopositive cells had a relatively round profile and were assumed to be acinar cells. The positive staining decreased thereafter and disappeared completely by PD11. To confirm the identity of cells positive for FGF-6, double immunolabeling with anti-alphasmooth muscle actin (alphaSMA) and anti-FGF-6 antibodies was performed. The positive staining of alphaSMA, a marker of myoepithelial cells, was detected in the flattened cells surrounding the acini but not in the cells positive for FGF-6. The staining properties of secretory granules in acinar cells were also examined with periodic acid-Shiff (PAS) and alcian blue (AB). PAS-positive granules abundant in the late gestational stages (GD17 to PD0) began to be replaced with AB-positive mucous granules at early neonatal days (PD0-3), when the FGF-6/FGFR-4 expression was the strongest. These findings suggest that FGF-6/FGFR-4 might be involved in the changes of secretory granule content of acinar cells in the sublingual gland during the late gestational and early neonatal stages.

Patterns and variability in electrophoretic polypeptide profiles of human saliva in a healthy population.

Electrophoretic polypeptide profiles of normal human saliva differ markedly between different reports. Since both methodological variations and polymorphism may explain these differences, in this study we aimed to establish whether or not the salivary electrophoretic polypeptide profiles of subjects from a healthy population share discrete molecular features. To this end, parotid, submandibular/sublingual and whole salivas were collected separately from each of 40 young and 34 elderly clinically healthy adults and processed for SDS-polyacrylamide gel electrophoresis and Coomassie blue staining. Each type of glandular saliva displayed a different group of invariant (i.e. present in every subject) electrophoretic polypeptide bands while whole saliva showed a profile that reflected mostly the combined contribution of the major salivary glands. Some minor variant (i.e. absent in some subjects) bands were identified in each type of saliva. Regarding those interindividual variations, no age- or sex-dependence was appreciated. Altogether, these results demonstrate the occurrence of distinctive electrophoretic polypeptide patterns, in addition to some minor variations, for each type of normal saliva, thus providing a background for further populational studies on salivary polypeptide profiles.

Role of thyroid hormone in the initiation of EGF (epidermal growth factor) expression in the sublingual gland of the postnatal mouse.

The effect of triiodo-L-thyronine (T3) and propylthiouracil (PTU) on the initiation of epidermal growth factor (EGF) expression in the sublingual glands (SLGs) of postnatal mice was investigated by indirect enzyme-labeled and immunogold antibody methods for light and electron microscopy, respectively. In normal males, EGF immunoreactivity first appeared in a few scattered granular cells of striated ducts (SDs) at 5 weeks of age, and the immunoreactive cells had increased in number at 6 weeks of age. No EGF expression was observed in the glands of females at any ages examined. When T3 (1 mg/kg body weight) was given to males every other day for 2 weeks before examination, EGF expression began earlier; the immunoreactive granular cells were first detected at 4 weeks of age, and at later ages they were markedly increased in number compared to those of normal males. Moreover, T3 was capable of inducing EGF in the female glands. After T3 was administered to females in the same manner as in males, a few immunoreactive cells were first detected at 5 weeks of age, and increased numbers were detected at later ages. By contrast, when PTU (1 mg/kg body weight) was given to male mice every other day for 2 weeks before examination, the EGF-immunoreactive cells were markedly decreased in number compared to those of normal males of the same age. Electron microscopy revealed that many SD cells contained secretory granules, and that these cells constituted the granular striated tubule (GST) in a portion of SDs, but they were undetectable by light microscopy, because their secretory granules were minimal in size and few in number. Gold-labeling of EGF was confined to the secretory granules of scattered granular cells, whose secretory granules were far larger in size and more abundant than those of the GST cells. These results suggest that thyroid hormone is essential to differentiation of the cellular phenotype of GST precursor cells into typical granular cells (detectable by light microscopy) that express EGF in the mouse SLG, showing a close resemblance to the submandibular granular convoluted tubule cells.

The sld mutation is specific for sublingual salivary mucous cells and disrupts apomucin gene expression.

NFS/N-sld mice harbor a spontaneous autosomal recessive mutation, sld (sublingual gland differentiation arrest) and histologically display attenuated mucous cell expression in sublingual glands (Hayashi et al. Am J Pathol 132: 187-191, 1988). Because altered serous demilune cell expression is unknown, we determined the phenotypic expression of this cell type in mutants. Moreover, we evaluated whether absence of glycoconjugate staining in 3-day-old mutant glands is related to disruption in apomucin gene expression and/or to posttranslational glycosylation events. Serous cell differentiation is unaffected, determined morphologically and by serous cell marker expression (PSP, parotid secretory protein; and Dcpp, demilune cell and parotid protein). Conversely, apical granules in "atypical" exocrine cells of mutant glands are PSP and mucin negative, but contain abundant SMGD (mucous granule marker). Age-related appearance of mucous cells is associated with expression of apomucin gene products, whereas SMGD expression is unaltered. "Atypical" cells thus appear specified to a mucous cell fate but do not synthesize mucin glycoproteins unless selectively induced postnatally, indicating the sld mutation disrupts apomucin transcriptional regulation and/or decreases apomucin mRNA stability.

Immunolocalization of PTHrP in the sublingual glands of three mammals.

The present study deals with immunohistochemical localization of PTHrP in sublingual glands of white mouse, bank vole, and common vole. PTHrP immunoreactivity was observed in epithelial cells of striated, interlobular and main excretory ducts of the salivary glands in all the three animal species tested. However, we found no positive reaction for PTHrP in epithelial cells of the intercalated ducts. In striated duct cells, the reaction intensity was species-dependent. In bank vole and common vole, the reaction was very strong, while in white mouse very weak. In the remaining segments of excretory ducts (interlobular and main excretory duct) we found no species-related differences in the reaction intensity or character. Myoepithelial cells surrounding ducts and mucous tubules with serous demilunes in sublingual glands were also PTHrP-negative in all the three animal species tested.

Proliferation and distribution of myoepithelial cells during atrophy of the rat sublingual gland.

BACKGROUND: The present study was aimed to determine the proliferation and distribution of myoepithelial cells during atrophy of rat sublingual glands. METHODS: The excretory duct of the right sublingual gland of rats was doubly ligated with metal clips to induce atrophy in the gland. The atrophic sublingual glands were taken from 1 to 28 days after duct ligation and examined with single immunohistochemistry for actin as a marker of myoepithelial cells and with immunohistochemical double staining for actin and proliferating cell nuclear antigen (PCNA) as a marker of proliferating cells. RESULTS: In unligated sublingual glands, myoepithelial cells embraced acini and intercalated ducts, but not striated and interlobular excretory ducts. In the early stages of atrophy, myoepithelial cells surrounded small ducts but not large ones. However, in the later stages of atrophy, myoepithelial cells were also observed at the periphery of the large ducts. The immunohistochemical double staining showed that there were PCNA-positive myoepithelial cells in the normal as well as in the atrophic sublingual glands. However, the PCNA labeling indices of myoepithelial cells were low in the unligated and atrophic sublingual glands, and there were no statistically significant differences in these labeling indices. CONCLUSION: The observations suggest that the distribution of myoepithelial cells change during atrophy of rat sublingual glands and that myoepithelial cells have low proliferative activity in both the normal and atrophic condition of rat sublingual glands.

Localisation of epidermal growth factor receptor in mucous cells of human salivary glands.

EGFR activation has been related to an increase in synthesis and secretion of mucins in epithelial cells, so that the use of EGFR tyrosine kinase inhibitors has been proposed in the therapy of mucin hypersecretory diseases. In this paper, we describe the ultrastructural localisation of EGFR in the mucous elements of human major and minor salivary glands and relate it to mucin distribution. A post-embedding immunogold staining method has been applied to normal surgical samples of human submandibular, sublingual, and labial glands, using a mouse monoclonal antibody specific for the intracellular domain of human EGFR. In mucous cells of all the glands examined, specific reactivity was detected in the cytoplasmic basolateral portions and near the mucous droplets, but not on cell surfaces. Since this pattern of labelling must be related to the internalisation process of the ligand-GFR complex, our results support the hypothesis that EGFR activation takes place in mucous cells and affects mucin production in human salivary glands.

[Assessment of peripheral blood perfusion during open heart surgery with sublingual PCO2 measured by ISFET-PCO2 sensor].

Sublingual tissue PCO2 (PSLCO2) was continuously monitored with an ISFET-based PCO2 sensor during and after the open-heart surgery under cardiopulmonary bypass (CPB) in order to study the effect of CPB on the peripheral blood perfusion. In addition, PSLCO2 monitoring was carried out in several cases of off-pump CABG. In the cases of open-heart surgery with CPB, PSLCO2 increased from 35.0 +/- 5.6 mmHg at the induction of anesthesia to the maximum value of 55.7 +/- 6.0 mmHg during CPB. After declamping of the aorta, PSLCO2 decreased gradually to 49.0 +/- 4.0 mm Hg 6 hr after the admission to ICU. The value of arterial lactate as another index of peripheral blood perfusion also increased gradually after the start of CPB, reaching to the maximum value of 8.8 +/- 1.1 mmol.l-1 just after being admitted into ICU. In the case of off-pump CABG, PSLCO2 and arterial lactate showed a slight increase during the later part of the surgery, but the change was not so significant as in the case of open-heart surgery under CPB. Through this study, typical changing pattern of PSLCO2 during the open-heart surgery was recognized. The change of PSLCO2 always preceded that of arterial lactate. We also experienced one case in which early stage of hypoperfusion was detected through the monitoring of PSLCO2. These results suggest clinical advantages of PSLCO2 monitoring.

Seromucous cells in human sublingual glands: examination by immunocytochemistry of lysozyme.

This study examined the occurrence and morphological features of serous-type cells in human sublingual gland, using immunocytochemistry for lysozyme. Lysozyme-positive cells usually formed demilunes and occasionally their own acini. They were also found among cells of an intercalated duct and in its immature acinus consisting of a small number of secretory cells. All these serous cells could be classified as seromucous cells because they simultaneously revealed reactivity for mucus, i.e., a periodic acid-Schiff (PAS) and a periodic acid-thiocarbohydrazide-silver proteinate (PA-TCHSP) reaction under the light- and electron-microscope, respectively. Immunogold labeling of lysozyme in the seromucous cells was distributed on variously sized secretory granules. These usually possessed a single electron-dense spherule in an electron-lucent matrix, while granules of a homogenous structure were also present. Lysozyme-positive cells filled with large, lucent secretory granules could hardly be morphologically distinguished from the lysozyme-negative mucous cells; they corresponded to "intermediate" cells designated under the light microscope. All "immature" secretory cells with only a few secretory granules were also lysozyme-positive seromucous cells. The present study demonstrated that the seromucous cells in the human sublingual glands conform closely with those in the human labial glands (MIYAZAKI et. al., 1998).

Immunohistochemical localization of S100A1 and S100A6 in postnatally developing salivary glands of rats.

S100 proteins are calcium-binding proteins of the EF-hand superfamily and are involved in the regulation of a number of cellular processes. The present study deals with the immunohistochemical expression of S100A1 and S10100A6 in the rat submandibular and sublingual glands during postnatal development from day 0 to 12 weeks. Expression of S100A1 was particularly concentrated in pillar and transition cells in the granular convoluted tubule (GCT) and in striated duct cells of the submandibular gland age 4 weeks to maturity. None or only weak staining for S100A1 was observed in the duct segment at 0-5 days. On the contrary, immunostaining of S100A6 was present in proacinar cells in undifferentiated submandibular gland at age 3 days to 2 weeks. S100A6 immunoreactivity in rat submandibular gland coexisted with chromogranin reactivity. It is possible that S100A6 regulates secretion of chromogranin in proacinar cells. Secretion of growth factors and biologically active peptides in the GCT are regulated by calcium signals, and S100A1 may be involved in the secretory mechanism of granular cells. S100A1 and S100A6 are potentially of great importance in secretory functions of granular cells and proacinar cells, as well as in rat salivary glands.

Salivary gland nucleotide receptors: evidence for functional expression of both P2X and P2Y subtypes.

A growing body of information now supports the suggestion that P2 receptors for extracellular nucleotides (primarily ATP) have a role in regulating salivary gland function. There is solid pharmacological and molecular evidence for the presence of P2X ligand-gated ion channel nucleotide receptors (P2X4 and P2X7/P2Z). More recently, our group and others have obtained evidence that multiple P2Y G protein-coupled nucleotide receptors (P2Y1 and P2Y2) are also expressed. Our studies have focused on defining the conditions under which P2Y receptors are expressed, the functional consequences of their activation, and the importance of co-expression of P2X and P2Y receptors. Functional and molecular approaches have been used to identify the P2 subtypes in salivary glands and in salivary cell lines. Assays include measurement of changes in [Ca2+]i, changes in transcellular short circuit current in monolayers, and RT-PCR to assess changes in receptor mRNA levels. The main observations are: (1) P2Y1 receptor activity is present in the submandibular gland (SMG) of immature rats but decreases over the first four weeks following birth, although mRNA levels remain relatively constant; (2) P2Y2 receptors are present in the cell lines and are up-regulated during short-term culture of normal parotid, sublingual, and SMG cells and following ligation of the main excretory duct of SMG; and (3) the P2X subtypes, P2X4 and P2X7, and the P2Y subtypes, P2Y1 and P2Y2, are co-expressed in salivary glands and salivary cell lines, and exhibit distinct basolateral versus apical localization in polarized cell monolayers as well as discrete patterns of intracellular signaling.

In vitro studies of the regulation of mucous gland secretion.

Our laboratory is concerned with elucidation of mechanisms regulating the exocrine secretion of mucin glycoproteins by mucous cells of salivary mucous glands. As a model system for our studies we use short-term cultures of acinar structures isolated from rat sublingual glands. Recent results are discussed from an on-going study of cross-talk between the two primary signaling pathways regulating exocrine secretion from isolated sublingual acini: the muscarinic cholinergic and vasoactive intestinal peptide (VIP) pathways. The combination of muscarinic agonist (carbachol) and VIP elicits a secretion equivalent to about 150% of the additive sum of the secretory responses to each agonist alone. This synergistic secretory response is only observed at submaximal concentrations of carbachol. VIP thus serves to decrease the EC50 for carbachol nearly three-fold. Results are thus far consistent with the hypothesis that a sustained rise in the intracellular concentration of calcium ions induced by VIP accounts for synergistic secretion and the heightened sensitivity to carbachol.

Confocal and electron microscopy to characterize sialoglycoconjugates in mouse sublingual gland acinar cells.

Double lectin labeling for confocal microscopy and lectin-protein A-gold binding for electron microscopy were applied to the mouse sublingual gland in order to study surface and cytoplasmic sialoglycoconjugates. For this purpose, serially cut sections were submitted to sialidase followed by incubation with lectins recognizing usually acceptor sugars for terminal sialic acids. At the electron microscope level, the residues subtended to sialic acid were individually identified on adjacent sections by an indirect technique of labeling, whereas with confocal microscopy the above sugars were simultaneously visualized on the same section by a double staining method using fluorescein isothiocyanate (FITC)- and tetramethylrhodamine isothiocyanate (TRITC)-conjugated lectins. Acinar cells were found to contain the terminal sequence sialic acid-beta-galactose in abundance while the sequence sialic acid-alpha-N-acetylgalactosamine appeared to be present in modest amounts. Both sialoglycoconjugates were homogeneously codistributed inside acinar cells. The combination with a saponification method also allowed the occurrence of C4 acetylated sialic acids linked to beta-galactose to be discovered, at the electron microscope level, on acinar cell secretory products.

Sex-dependent differences in the concentrations of the principal neurotransmitters, noradrenaline and acetylcholine, in the three major salivary glands of mice.

The concentrations of principal neurotransmitters in the submandibular, parotid and sublingual glands were compared between two pairs of age-matched male and female ddY mice, one pair consisting of 4-week-old and the other 8-week-old animals. Sex-dependent differences in both noradrenaline and acetylcholine concentrations were observed only in the submandibular gland, although each neurotransmitter showed distinct features. The acetylcholine concentration in the submandibular gland was higher in the female at both ages, whereas the noradrenaline concentration was higher in the female at the age of 4 weeks but became higher in the male by the age of 8 weeks. On the other hand, the total amounts of noradrenaline and acetylcholine per submandibular gland were already greater in the male at 4 weeks, and the male parotid and sublingual glands also had a greater noradrenaline content by 4 weeks and 8 weeks, respectively. Each type of gland had similar growth rates over the 4-week period, and the male submandibular and parotid glands were heavier than the female. In addition, each type of gland had its characteristic ratio of noradrenaline to acetylcholine concentration, which did not differ between the sexes and remained in similar basic patterns during the period examined, except for the submandibular gland of 8-week-old male mice, which developed greater amounts of the sympathetic neurotransmitter noradrenaline.