Shh/Ptch and EGF/ErbB cooperatively regulate branching morphogenesis of fetal mouse submandibular glands.

The hedgehog family includes Sonic hedgehog (Shh), Desert hedgehog, and Indian hedgehog, which are well known as a morphogens that play many important roles during development of numerous organs such as the tongue, pancreas, kidney, cartilage, teeth and salivary glands (SMG). In Shh null mice, abnormal development of the salivary gland is seen after embryonic day 14 (E14). Shh also induced lobule formation and lumen formation in acini-like structures in cultured E14 SMG. In this study, we investigated the relationship between Shh and epidermal growth factor (EGF)/ErbB signaling in developing fetal mouse SMG. Administration of Shh to cultured E13 SMG stimulated branching morphogenesis (BrM) and induced synthesis of mRNAs for EGF ligands and receptors of the ErbB family. Shh also stimulated activation of ErbB signaling system such as ERK1/2. AG1478, a specific inhibitor of ErbB receptors, completely suppressed BrM and activation of EGF/ErbB/ERK1/2 cascade in E13 SMGs cultured with Shh. The expressions of mRNA for Egf in mesenchyme and mRNA for Erbb1, Erbb2 and Erbb3 in epithelium of E13 SMG were specifically induced by administration of Shh. These results show that Shh stimulates BrM of fetal mouse SMG, at least in part, through activation of the EGF/ErbB/ERK1/2 signaling system.

Variability of breathing during wakefulness while using CPAP predicts adherence.

BACKGROUND AND OBJECTIVE: The standard therapy for obstructive sleep apnoea (OSA) is continuous positive airway pressure (CPAP) therapy. However, long-term adherence remains at ~50% despite improvements in behavioural and educational interventions. Based on prior work, we explored whether regularity of breathing during wakefulness might be a physiologic predictor of CPAP adherence. METHODS: Of the 117 consecutive patients who were diagnosed with OSA and prescribed CPAP, 79 CPAP naïve patients were enrolled in this prospective study. During CPAP initiation, respiratory signals were collected using respiratory inductance plethysmography while wearing CPAP during wakefulness in a seated position. Breathing regularity was assessed by the coefficient of variation (CV) for breath-by-breath estimated tidal volume (VT ) and total duration of respiratory cycle (Ttot). In a derivation group (n = 36), we determined the cut-off CV value which predicted poor CPAP adherence at the first month of therapy, and verified the validity of this predetermined cut-off value in the remaining participants (validation group; n = 43). RESULTS: In the derivation group, the CV for estimated VT was significantly higher in patients with poor adherence than with good adherence (median (interquartile range): 44.2 (33.4-57.4) vs 26.0 (20.4-33.2), P < 0.001). The CV cut-off value for estimated VT for poor CPAP adherence was 34.0, according to a receiver-operating characteristic (ROC) curve. In the validation group, the CV value for estimated VT >34.0 confirmed to be predicting poor CPAP adherence (sensitivity, 0.78; specificity, 0.83). CONCLUSION: At the initiation of therapy, breathing regularity during wakefulness while wearing CPAP is an objective predictor of short-term CPAP adherence.

Mini Nutritional Assessment Short-Form predicts exacerbation frequency in patients with chronic obstructive pulmonary disease.

BACKGROUND AND OBJECTIVE: Exacerbations of chronic obstructive pulmonary disease (COPD) are a major cause of morbidity, mortality and reduced health status. Thus, to predict and prevent exacerbations is essential for the management of COPD. The aims of this study were to determine whether nutritional status as assessed by the Mini Nutritional Assessment Short-Form (MNA-SF) predicts COPD exacerbation and to compare the ability of the MNA-SF to predict COPD exacerbation with that of the COPD Assessment Test (CAT). METHODS: Pulmonary function, the modified Medical Research Council (mMRC) scale and body mass index (BMI) were evaluated in 60 stable patients with COPD (mean age, 72 years; mean forced expiratory volume in 1 s (FEV1 ), 51.1% predicted). The MNA-SF and CAT were also completed. Exacerbations were recorded prospectively for 1 year after the initial assessment. RESULTS: The mean MNA-SF score was 11.4 ± 2.4 (well nourished, 51%; at risk, 37%; and malnourished, 12%). The mean CAT score was 14.4 ± 7.5 (low impact, 37%; medium impact, 38%; high impact, 20%; and very high impact, 5%). The CAT scores were significantly associated with the mMRC scale and %FEV1, but were not associated with BMI and the MNA-SF score. The exacerbation frequency was associated with the MNA-SF score but not with the CAT score. CONCLUSIONS: The MNA-SF predicts COPD exacerbation independently of the CAT.

Distribution of bone mineral content is associated with body weight and exercise capacity in patients with chronic obstructive pulmonary disease.

BACKGROUND: Although low bone mineral density is highly prevalent in patients with chronic obstructive pulmonary disease (COPD), the distribution of the reduced bone mass has not been fully elucidated. OBJECTIVES: To determine regional bone mass loss in patients with COPD and investigate whether the change in distribution may be associated with body weight loss and functional capacity. METHODS: Body mass index (BMI) was assessed, and height squared indices were derived for the bone mineral content index (BMCI) of the arms, legs and trunk by dual-energy X-ray absorptiometry in 45 male patients with COPD and 12 age- and sex-matched control subjects. Pulmonary function tests were performed, and maximal oxygen uptake (VO2max) was measured. RESULTS: The BMCI was lower in the total bone, legs and trunk of patients with COPD than in control subjects, although the BMCI in the arms was similar between the groups. BMI correlated significantly with the BMCI in all 3 segments. Bone mineral content (BMC) in the trunk, expressed as a percentage of total BMC (BMC trunk/total BMC), correlated significantly with BMI. The BMCI in the trunk was closely related with VO2max but not with airflow limitation. CONCLUSIONS: There was a regional difference in BMC reduction, but a predominant reduction of bone mass in the trunk was not associated with the severity of airflow limitation but rather with body weight loss and exercise intolerance. These data suggest that body weight loss and exercise intolerance are important risk factors for vertebral fracture in patients with COPD.

The impact of obstructive sleep apnea and nasal CPAP on circulating adiponectin levels.

PURPOSE: Although obstructive sleep apnea syndrome (OSAS) is known to be an important risk factor for cardiovascular diseases, the mechanism behind this association has not been fully elucidated. Transendothelial migration of monocytes mediated by adhesion molecules is a crucial step in the pathogenesis of atherosclerosis. We investigated the effect of hypoxic stress on plasma adiponectin and tumor necrosis factor-α (TNF-α) levels and whether adiponectin and TNF-α modulate adhesion molecules in patients with OSAS. METHODS: In 22 patients, plasma adiponectin and TNF-α levels and serum concentrations of soluble intercellular adhesion molecule-1 (sICAM-1) were determined early in the morning after polysomnography and after nasal continuous positive airway pressure (nCPAP) treatment. RESULTS: Plasma adiponectin levels were inversely correlated with the apnea-hypopnea index (AHI) (r = -0.582, p < 0.005) and % time in SpO2 <90 % (r = -0.539, p < 0.01) but not with the body mass index (BMI). TNF-α levels were positively correlated with the AHI (r = 0.462, p < 0.05) and BMI (r = 0.452, p < 0.05). Serum sICAM-1 levels were inversely correlated with plasma adiponectin levels (r = -0.476, p < 0.05) but not with TNF-α levels. Although plasma TNF-α levels decreased after overnight nCPAP treatment (p < 0.05), plasma adiponectin levels increased after long-term nCPAP (3 months) treatment (p < 0.02) in ten patients. CONCLUSIONS: Our findings suggest that reduced adiponectin and elevated TNF-α levels in plasma are associated with OSAS-induced hypoxic stress. Decreased adiponectin levels are associated with sICAM-1 levels.

Autoimmune Encephalitis Associated with Anti-N-methyl-D-aspartate Receptor and Anti-Hu Antibodies Successfully Treated with Carboplatin and Etoposide for Small-cell Lung Cancer.

The coexistence of multiple autoantibodies associated with autoimmune encephalitis (AE) is rare. A 63-year-old woman developed psychosis and consciousness disorder. Her cerebrospinal fluid was positive for anti-N-methyl-D-aspartate receptor antibodies, and her serum was positive for anti-Hu antibodies. Enhanced computed tomography revealed a mass in the right pulmonary hilum. AE complicated with small-cell lung cancer was diagnosed. Immunotherapy (steroid therapy and intravenous immunoglobulin) and four courses of carboplatin-etoposide chemotherapy were required to improve her neurological symptoms. When the coexistence of multiple antibodies is detected, despite its rarity, aggressive detection and treatment of any underlying malignancy may be recommended.

Mesenchymal miR-21 regulates branching morphogenesis in murine submandibular gland in vitro.

Branching morphogenesis in murine submandibular glands (SMG) is regulated by growth factors, extracellular matrix (ECM) and many biological processes through interactions between the epithelium and the mesenchyme. MicroRNAs (miRNAs) are a set of small, non-protein-coding RNAs that regulate gene expression at the post-transcriptional level. We hypothesized that branching morphogenesis is partly regulated by miRNAs. Forty-four miRNAs and novel miRNA candidates were detected in SMG at embryonic day 13 by a cloning method combined with Argonaute-2 immunoprecipitation. MicroRNA21 (miR-21) expression in the mesenchyme was up-regulated and accelerated by epidermal growth factor, which is known to enhance branching morphogenesis in vitro. Down-regulation of miR-21 in the mesenchyme by locked nucleic acids was associated with a decrease in the number of epithelial buds. Relative quantification of candidates for target genes of miR-21 indicated that two messenger RNAs (for Reck and Pdcd4) were down-regulated in the mesenchyme, where miR-21 expression levels were up-regulated. These results suggest that branching morphogenesis is regulated by miR-21 through gene expression related to ECM degradation in the mesenchyme.

Reduced larger von Willebrand factor multimers at dawn in OSA plasmas reflect severity of apnoeic episodes.

Plasma von Willebrand factor (VWF), produced in and released from vascular endothelial cells by various stimuli including hypoxia, induces platelet aggregation under high shear stress and plays dual pivotal roles in haemostasis and thrombosis within arterioles, which are regulated by the size of vWF multimers (VWFMs). Patients with obstructive sleep apnoea (OSA) have increased risk of thrombotic cardiovascular events, but the pathogenesis is unclear. We examined the relationship between VWF and OSA by measuring VWF antigen (VWF:Ag), VWFMs, VWF collagen binding activity (VWF:CB) and a disintegrin-like, metalloproteinase, and thrombospiondin type 1 motifs 13. A total of 58 OSA patients were enrolled. Blood samples were collected before sleep, after sleep, and after one night of nasal continuous positive airway pressure therapy. Based on VWFM analysis, OSA patients were classified into three groups; consistently normal VWFMs (group 1, n=29), increased high molecular weight (HMW)-VWFMs at 06:00 h (group 2, n=18), and decreased or absent HMW-VWFMs at 06:00 h (group 3, n=11). Patients in group 3 had significantly worse apnoea/hypopnoea index; VWF:CB followed a similar pattern. We observed a significant decrease in platelet count between 21:00 h and 06:00 h in OSA patients, potentially associated with reduced larger VWFMs together with decreased VWF:Ag levels. Severe OSA may contribute to an arterial pro-thrombotic state.

Extracellular regulated kinase5 is expressed in fetal mouse submandibular glands and is phosphorylated in response to epidermal growth factor and other ligands of the ErbB family of receptors.

Growth factors and their receptors regulate development of many organs through activation of multiple intracellular signaling cascades including a mitogen-activated protein kinase (MAPK). Extracellular regulated kinases (ERK)1/2, classic MAPK family members, are expressed in fetal mouse submandibular glands (SMG), and stimulate branching morphogenesis. ERK5, also called big mitogen-activated protein kinase 1, was recently found as a new member of MAPK super family, and its biological roles are still largely unknown. In this study, we investigated the expression and function of ERK5 in developing fetal mouse SMGs. Western blotting analysis showed that the expression pattern of ERK5 was different from the pattern of ERK1/2 in developing fetal SMGs. Both ERK1/2 and ERK5 were phosphorylated after exposure to ligands of the ErbB family of receptor tyrosine kinases (RTKs). Phosphorylation of ERK1/2 was strongly induced by epidermal growth factor (EGF) in SMG rudiments at embryonic day 14 (E14), E16 and E18. However, ERK5 phosphorylation induced by EGF was clearly observed at E14 and E16, but not at E18. Branching morphogenesis of cultured E13 SMG rudiments was strongly suppressed by administration of U0126, an inhibitor for ERK1/2 activation, whereas the phosphorylation of ERK5 was not inhibited by U0126. BIX02188, a specific inhibitor for ERK5 activation, also inhibited branching morphogenesis in cultured SMG rudiments. These results show that EGF-responsive ERK5 is expressed in developing fetal mouse SMG, and suggest that both ERK1/2 and ERK5 signaling cascades might play an important role in the regulation of branching morphogenesis.

P2Y11 purinoceptor mediates the ATP-enhanced chemotactic response of rat neutrophils.

ATP and hydrolysis products of ATP like adenosine regulate the chemotaxis of neutrophils by activating purinoceptors and adenosine receptors. The present study was designed to examine exogenous ATP, activation of purinoceptors, and activation of A(3) adenosine receptor as key steps in the signal cascades that control cell orientation and migration of rat neutrophils. One or more of those steps might be potential therapeutic targets for treatment of inflammatory diseases. The chemotaxis of rat neutrophils was stimulated with N-formyl-methionyl-leucyl-phenylalanine (fMLP) and measured with an EZ-TAXIScan apparatus. The effects of apyrase, exogenous ATP, suramin (P2X and P2Y blocker), PPADS (a P2X blocker), TNP-ATP (P2X(1) and P2X(3) antagonist), and Reactive Blue 2 (a P2Y blocker) on the chemotactic response were also investigated. Rat neutrophil chemotaxis was significantly suppressed by apyrase. fMLP induced rat neutrophil chemotaxis was potentiated by ATP, blocked by suramin, not affected by PPADS or TNP-ATP, and significantly inhibited by RB-2. Western blotting showed that A(3), P2Y(2), and P2Y(11) were expressed in rat neutrophils. The chemotactic response of rat neutrophils to fMLP stimulation is potentiated by ATP via P2Y(11) purinoceptors but not P2X purinoceptors or A(3) adenosine receptor, and that the response plays a critical role in host defense and pathogenicity.

Notch activation induces the generation of functional NK cells from human cord blood CD34-positive cells devoid of IL-15.

The development of NK cells from hematopoietic stem cells is thought to be dependent on IL-15. In this study, we demonstrate that stimulation of human cord blood CD34(+) cells by a Notch ligand, Delta4, along with IL-7, stem cell factor, and Fms-like tyrosine kinase 3 ligand, but no IL-15, in a stroma-free culture induced the generation of cells with characteristics of functional NK cells, including CD56 and CD161 Ag expression, IFN-gamma secretion, and cytotoxic activity against K562 and Jurkat cells. Addition of gamma-secretase inhibitor and anti-human Notch1 Ab to the culture medium almost completely blocked NK cell emergence. Addition of anti-human IL-15-neutralizing Ab did not affect NK cell development in these culture conditions. The presence of IL-15, however, augmented cytotoxicity and was required for a more mature NK cell phenotype. CD56(+) cells generated by culture with IL-15, but without Notch stimulation, were negative for CD7 and cytoplasmic CD3, whereas CD56(+) cells generated by culture with both Delta4 and IL-15 were CD7(+) and cytoplasmic CD3(+) from the beginning and therefore more similar to in vivo human NK cell progenitors. Together, these results suggest that Notch signaling is important for the physiologic development of NK cells at differentiation stages beyond those previously postulated.

A refined two-hybrid system reveals that SCF(Cdc4)-dependent degradation of Swi5 contributes to the regulatory mechanism of S-phase entry.

Ubiquitin-dependent degradation is implicated in various cellular regulatory mechanisms. The SCF(Cdc4) (Skp1, Cullin/Cdc53, and the F-box protein Cdc4) complex is an ubiquitin ligase complex that acts as a regulator of cell cycle, signal transduction, and transcription. These regulatory mechanisms are not well defined because of the difficulty in identifying the interaction between ubiquitin ligases and their substrates. To identify substrates of the yeast SCF(Cdc4) ubiquitin ligase complex, we refined the yeast two-hybrid system to allow screening Cdc4-substrate interactions under conditions of substrate stabilization, and identified Swi5 as a substrate of the SCF(Cdc4) complex. Swi5 is the transcriptional activator of Sic1, the inhibitor of S phase cyclin-dependent kinases (CDKs). We showed that Swi5 is indeed ubiquitinated and degraded through the SCF(Cdc4) complex. Furthermore, the SCF(Cdc4)-dependent degradation of Swi5 was required to terminate SIC1 transcription at early G(1) phase, which ensured efficient entry into S phase: Hyperaccumulation of Sic1 was noted in cells expressing stabilized Swi5, and expression of stabilized Swi5 delayed S phase entry, which was dominantly suppressed by SIC1 deletion. These findings indicate that the SCF(Cdc4) complex regulates S phase entry not only through degradation of Sic1, but also through degradation of Swi5.

Differential regulation of splenic CD8- dendritic cells and marginal zone B cells by Notch ligands.

The importance of Notch signaling to maintain CD8- dendritic cells (DCs) in the spleen has recently been revealed. However, the ligand responsible for this Notch signaling has not been determined yet. In this study, we demonstrated that blocking of Delta-like (Dll) 1 alone had no significant effect on the maintenance of CD8- DCs while marginal zone (MZ) B cells were significantly reduced in the spleen of mice. On the other hand, blocking of Dll1, Dll4, Jagged1 and Jagged2 significantly decreased CD8- DCs. All these Notch ligands are expressed predominantly in the red pulp of the spleen where CD8- DCs reside. These results indicate a differential regulation of CD8- DCs and MZ B cells by Notch ligands in the spleen.

[Clinical analysis of eight patients with pulmonary toxocariasis].

We encountered 8 adult cases of pulmonary toxocariasis. Five were asymptomatic, 1 had transient chest pain, 1 suffered from arthralgia and migrating skin pain, and 1 had chest discomfort due to pneumothorax. Infection was associated with the consumption of raw liver with paratenic hosts in 5 patients. The cause was suspected to be contact with infected young dogs in 1 case and was undetermined in 2 cases. All 8 cases showed some abnormalities in their laboratory examination results including eosinophilia (>500/microl) and elevated IgE (>100 IU), and all had positive results in serological examinations for the larval excretory-secretory product of Toxocara canis. In 7 patients, excluding the patient with pneumothorax, chest computed tomography demonstrated multiple small pulmonary lesions, most of which were either nodules with halos, or ground-glass opacities. One patient recovered without medication, while the other 7 were treated with albendazole (ABZ) with good responses. Although the optimal duration of ABZ therapy has not been established, 4 weeks or longer seemed necessary to obtain a complete cure in pulmonary toxocariasis.

Delta-like 1 is essential for the maintenance of marginal zone B cells in normal mice but not in autoimmune mice.

Notch2 and Delta-like 1 (Dll1) have been implicated in the development of marginal zone B (MZB) cells. In the present study, we characterized the expression and function of mouse Notch receptors and ligands in the spleen by using newly generated mAbs. Although Notch2 was expressed on both B and T cells in the spleen, the highest expression was observed on precursors of marginal zone B and MZB cells. Dll1 was expressed on macrophage and erythroblasts in the red pulp, but not on B cells or marginal zone macrophage. Administration of a blocking mAb against Dll1 not only blocked the development of MZB cells in juvenile mice but also gradually depleted the pre-established MZB cells in adult mice, indicating a critical role for Dll1 in the maintenance of MZB cells in the spleen of normal mice. Interestingly, Dll1 was not necessary for the maintenance of MZB cells in lupus-prone (NZB x NZW) F1 mice particularly after the onset of the disease, suggesting that the Dll1 independence may be a feature of dysregulated MZB cells producing auto-antibodies.

Nocturnal hypoxic stress activates invasive ability of monocytes in patients with obstructive sleep apnoea syndrome.

BACKGROUND AND OBJECTIVE: Obstructive sleep apnoea syndrome (OSAS) is known to be a risk factor for cardiovascular events. However, the precise mechanism has not been fully elucidated. OSAS-induced hypoxic stress may promote the production of inflammatory cytokines and chemokines by monocytes, which has a crucial role in the development of atherosclerosis. In addition, adhesion to the vascular endothelium and transendothelial migration of monocytes are considered to induce atherosclerosis. The aim of this study was to investigate the effects of hypoxic stress on the invasive ability of monocytes in OSAS. METHODS: Twenty-one male patients with OSAS and 17 healthy male control subjects, who were matched for age and BMI, were enrolled. Venous blood samples were collected before and after sleep, and also after CPAP titration, for the purpose of monocyte isolation. The invasive ability of monocytes was evaluated by counting the number of invading cells using a BD BioCoat Matrigel Invasion Chamber. RESULTS: The number of cells, which represents the invasive ability of monocytes, was significantly higher in patients with OSAS compared with control subjects, in the early morning (P < 0.001). In patients with OSAS, invasive ability in the early morning after sleep was significantly elevated as compared with that before sleep (P < 0.001), and was positively correlated with the oxygen desaturation index (P < 0.05). CPAP titration led to a decrease in the invasive ability (P < 0.001). CONCLUSIONS: These results indicate that OSAS-induced hypoxic stress activates the invasive ability of monocytes, and that the occurrence of this phenomenon during sleep may contribute to the development of atherosclerosis in OSAS.

Effect of serum leptin levels on hypercapnic ventilatory response in obstructive sleep apnea.

BACKGROUND: Leptin levels have been reported to be higher in patients with obstructive sleep apnea (OSA) than in control subjects with matching age and body mass index (BMI). Although animal studies have shown that leptin augments hypercapnic ventilatory response (HCVR), the effect of leptin on HCVR has not been clarified in OSA. OBJECTIVES: To investigate whether leptin could augment HCVR during wakefulness in patients with OSA. METHODS: Of 134 consecutive patients with OSA, 13 eucapnic and 16 hypercapnic patients with OSA, and 12 control subjects matched for sex, age, and BMI were selected. Fasting serum leptin levels were collected, and HCVR during wakefulness assessed by the slope between minute ventilation and end-tidal PCO(2). RESULTS: There was a significant positive relationship between serum leptin levels and HCVR in the group including control subjects and eucapnic patients with OSA (r = 0.42, p < 0.05). Subgroup analyses suggest that serum leptin levels and HCVR were significantly higher in eucapnic patients with OSA than in control subjects. On the other hand, hypercapnic patients had lower HCVR than eucapnic patients (p < 0.05), whereas serum leptin levels were similar between the two OSA subgroups. CONCLUSION: Leptin levels and HCVR are correlated as long as the eucapnic condition is maintained. We speculate that a stimulating effect of leptin on HCVR may be masked by the hypoventilation state.

T serotypes and antimicrobial susceptibilities of group A streptococcus isolates from pediatric pharyngotonsillitis.

Group A streptococcus (GAS) is a major cause of pediatric pharyngotonsillitis. In this study we determined the T serotype and antimicrobial susceptibility of GAS isolates from Japanese children. From January to December 2006, a total of 438 isolates of GAS were obtained from pharyngeal swabs of 438 children with pharyngotonsillitis. The commonest T serotype was type 1 (110 strains, 25.1%), followed by type 12 (107, 24.4%) and type 4 (77, 17.6%). All GAS isolated from pharyngeal swabs were susceptible to beta-lactams (benzylpenicillin, amoxicillin, cefotaxime, ceftriaxone, imipenem, panipenem, and cefditoren) and vancomycin, but 19.6, 19.6, 3.2, 11.6, and 27.6% were resistant to erythromycin, clarithromycin, clindamycin, minocycline, and norfloxacin, respectively. Resistance varied considerably with the T serotype. In particular, type 4 isolates had the highest resistance (67.5, 67.5, 26.0, and 53.2% were resistant to erythromycin, clarithromycin, minocycline, and norfloxacin, respectively).

Temporary accumulation of glycogen in the epithelial cells of the developing mouse submandibular gland.

Temporary accumulation of glycogen in the epithelial cells of the developing mouse submandibular gland was examined under light microscopic histochemistry and electron microscopy. To avoid loss of water-soluble glycogen during histological tissue preparation, fixation with ethanol and embedding in hydrophilic glycol methacrylate resin was used for light microscopy, and high-pressure freezing/freeze substitution for electron microscopy. Glycogen was detected on periodic acid-Schiff stain, periodic acid-thiosemicarbazide-silver proteinate reaction, and the digestion test with alpha-amylase. On embryonic day 14, glycogen began to accumulate in the proximal portions of the developing epithelial cords. On embryonic day 17, marked glycogen particles were seen at the basal portion of the ductal epithelial cells and an abrupt increase of glycogen accumulation occurred in the secretory cells in the terminal bulbs. Ultrastructural observation indicated large clumps of glycogen particles localized in the basal portion of the terminal bulb cells. The initiation of glycogen accumulation preceded the formation of lumens in the ducts and terminal bulbs. Furthermore, proliferation analysis by bromodeoxyuridine labeling showed that this glycogen accumulation followed the cessation of the epithelial cell proliferation. Postnatally, glycogen accumulation in the terminal bulbs became gradually inconspicuous and completely disappeared by postnatal day 3, but that in the ducts was retained until around postnatal day 12. Temporary glycogen accumulation after the cell proliferation and before/during the lumen formation and secretory granule formation suggests significant involvement of the carbohydrate metabolism in the organogenesis of the submandibular gland.