Lipid analysis of the major salivary glands in streptozotocin-diabetic rats and the effects of insulin treatment

Two separate sets of experiments were performed on female Wistar rats made diabetic with streptozotocin: (1) a time-course study where groups of three animals were removed at weekly intervals, up to 4 weeks after induction of diabetes, with an age-matched group of control (normal) animals kept for 4 weeks; (2) six further animals were made diabetic and kept for 7 weeks; three of these were given insulin in the final week. At the required time the animals were anaesthetized and the salivary glands removed and preserved by fixation or freezing. The frozen tissues were later homogenized and the protein and lipid content analysed. Histologically, intracellular lipid droplets had accumulated in the majority of the diabetic salivary glands. In the time-course experiment, the visible amount of intracellular lipid reached a maximum after 2 weeks and then decreased, with a concomitant disappearance of interstitial lipid. The increased lipid content was not attributable to any one class. The fatty acid profiles of the glands showed an increase in the percentages of C18:0 (stearic acid) and C18:2w6 (linoleic acid) and a decrease in the percentages of C18:1w9 (oleic acid) and C20:4w6 (arachidonic acid). After 1 week of insulin treatment the lipid content and the fatty acid profiles returned to normal. Thus the effect of insulin on salivary gland lipid metabolism is rapid both in its occurrence and reversibility. The effects seen in the diabetic rats are considered to be due to a lack of insulin and not to the presence of streptozotocin.

Immunoreaction of keratin, actin, S-100 protein and rat-EGF in duct-ligated rat salivary glands

Duct-ligated submandibular and sublingual glands of rats were evaluated immunohistochemically for changes in keratin (MoAb 1164), actin, S-100 protein and rat-EGF (rEGF). Normal salivary glands were reactive for keratin, S-100 protein and rEGF in the granular convoluted tubule (GCT) and duct cells, and for actin in the myoepithelium. Submandibular glands showed a marked reduction of S-100 protein and rEGF staining following duct ligation, and no increased staining of proliferating epithelial cells of the late stage in duct ligated glands. Sublingual glands revealed no marked changes for actin staining in myoepithelial cells, irrespective of atrophic changes occurring in acinar and duct cells after duct ligation. Immunohistochemical patterns differed for each type of gland; changes associated with the obstructive lesion were more prominent in the submandibular gland.

Analysis of major histocompatibility complex (MHC) class I antigen in the rat salivary gland

This antigen was examined in rats of different ages (new-born, 3, 5, 7, 10, 12 and 14 days after birth and adult) by immunofluorescence and immunoelectron microscopy. Changes in each kind of salivary gland when graft versus host disease was induced in recipient rats were also investigated. Monoclonal antibodies (HAM 2 or OX 18) specific to rat MHC class I antigen were used and these were detected by FITC-conjugated anti-mouse immunoglobulin. With HAM 2, MHC class I antigen in the submandibular gland was mostly located in the secretory duct cells; this expression was first found 10 days after birth. The antigen was found on the cell surfaces of the secretory duct cells by immunoelectron microscopy. With OX 18, MHC class I antigen was mainly found in the secretory duct cells, but weak expression was also found in the acinar cells. Localization of the antigen, by HAM 2 and OX 18 was less evident in the secretory duct cells of parotid and sublingual glands. When graft versus host disease was induced, MHC class I antigen (HAM 2) was observed in both acinar and secretory duct cells of the submandibular gland.

A comparative quantitative histological investigation of atrophic changes in the major salivary glands of liquid-fed rats

Adult male rats were maintained on a wholly liquid diet for 9 days. The three pairs of major glands were removed, weighed, histologically sectioned and examined by stereological and morphometric techniques. The results were compared with the same glands from control rats maintained on normal hard diet and water, and the extent of the differences was compared between the three different types of gland. Up to 50% of the serous acinar volume in the parotid glands, but only 15% in the submandibular glands, was lost after liquid feeding. There was no loss of the mucous acinar tissue in the sublingual gland. Mean acinar diameters were reduced by 33% in parotids and 15% in submandibular glands after liquid feeding, whereas the mucous acini of the sublingual gland remained unaltered. The results point to varying levels of susceptibility to the loss of masticatory reflexes between the parotid serous acini and the submandibular serous acini, and show that the morphology of the sublingual mucous acini is independent of masticatory reflex stimulation. The reductions in acinar diameters suggest that most of the glandular atrophy after liquid feeding is due to acinar cell shrinkage rather than to losses of acinar cell numbers in both parotid and submandibular glands.

Effects of repeated infusions of substance P and vasoactive intestinal peptide on the weights of salivary glands subjected to atrophying influences in rats

1. The long-term influence of substance P (SP) and vasoactive intestinal peptide (VIP) on rat salivary gland weight was investigated after parasympathetic denervation or on feeding soft food. 2. The parotid gland lost about one-third of its weight within 4-5 days following parasympathetic post-ganglionic denervation or change in dietary regimen, from pellets to liquid diet, thought to reduce nerve reflex activity. 3. Daily i.v. infusions with SP or VIP diminished or largely prevented the fall in parotid gland weight, whereas infusions with pentagastrin, bethanechol and saline had no effect. The infusions were preceded by administration of alpha- and beta-adrenoceptor antagonists; these antagonists were also given to the control animals. 4. The effect of SP and VIP on the parotid gland weight appeared to be related to cell size rather than to cell number, as judged by measurements of RNA and DNA. 5. Observations on the two other major salivary glands underlined the fact that different gland types in the same animal behave differently. Parasympathetic preganglionic denervation (decentralization) lowered the weights of the sublingual and submandibular glands, whereas liquid diet only reduced the weight of the sublingual gland. SP and VIP did not affect the weights of the submandibular glands, but VIP prevented the slight fall in sublingual gland weight induced by liquid diet. 6. The present results suggest a trophic role in rats for SP and VIP on parotid glands and for VIP on sublingual glands. Such an influence may be exerted naturally as a result of their release from nerves containing these peptides around acini.

Intraosseous salivary gland tissue of the mandible mimicking a periapical lesion

A case of an unusual site of salivary gland tissue is presented. The lesion appeared as a radiolucency between the apices of the lateral incisor and canine in a 57-year-old male patient and simulated a periapical lesion. The canine was found vital.

Comparison of labial and sublingual salivary gland biopsies in the diagnosis of Sjögren's syndrome

This study was designed to compare labial and sublingual salivary gland biopsies in the diagnosis of Sjögren's syndrome (SS). Fourteen labial and 29 sublingual specimens were considered positive. There was a better correlation between infiltration of the ductal structure and the focus score in the sublingual salivary gland biopsy than in the labial salivary gland biopsy. Use of sublingual salivary gland biopsy as an additional diagnostic tool in SS is therefore suggested.

Histology of the major salivary glands

Major salivary glands are characterized by the presence of numerous excretory units that consist of acini and a peculiar duct system. Under normal conditions, sebaceous glands are annexed to the duct system in the parotid and the submaxillary glands. The excretion of the saliva is assisted by the myoepithelial cells, which play an important role in the morphology of several kinds of salivary gland tumors. Interstitial lymphocytes give rise to the formation of lymph nodes in the parotid gland. Heterotopic salivary tissue is found in many locations throughout the head and neck. Age-induced variations and reactive changes include oncocyte proliferation, fatty infiltration, squamous and mucous metaplasia, hyperplasia, atrophy, and regeneration. An analysis of the normal salivary gland structure permits a morphogenetic approach to an understanding of the variability in histologic types of salivary gland tumors.

Pouting sublinguals: enlarged salivary glands in myxoedema

Enlarged salivary glands are common in patients with hypothyroidism but this finding is not widely appreciated. Although chronic painless enlargement of the salivary glands was reported in papers published 50-60 years ago, mainly in German, it is not mentioned in current textbooks on the thyroid. Along with the parotids, the submandibular and especially the sublingual glands may be quite enlarged, and the enlargement can be a useful clue to the diagnosis of hypothyroidism. The gland enlargement regresses at least partly after thyroid replacement therapy.

The plunging ranula. Pathogenesis, diagnosis and management

Ranulas are cysts resulting from retention, or extravasation of saliva from the sublingual gland. Two varieties are described: a superficial or oral ranula and a cervical or plunging ranula. The plunging ranula is located below the mylohyoid muscle and may present as a swelling in the upper part of the neck. Four cases are described to illustrate that this condition can be the cause of a neck swelling. Aetiology, differential diagnosis and surgical management are also discussed. Recurrences are mainly due to unfamiliarity with this phenomenon and ignorance of its aetiology. Successful treatment of the plunging ranula consists of excision of the ipsilateral sublingual salivary gland, which is the source of this disorder, and intra-oral evacuation of the pseudocyst of the neck swelling. There is no need for an extensive neck dissection of the cervical extension.

Relations of the histopathology of sublingual and labial salivary glands to the clinical presentation in primary Sjögren's syndrome

This study was designed to further analyse the histopathologic appearance of the sublingual and labial salivary gland biopsies performed in 50 patients suspected of having Sjögren's syndrome (SS). Three kinds of lesions were evaluated: occurrence of foci (an aggregate of more than 50 lymphocytes), lymphocytic infiltration of the duct walls, and the remaining abnormalities (such as scattered lymphocyte infiltrates, interstitial sclerosis, dilatation and regression of ducts and acini). The occurrence of foci correlates well with SS and even better when there is a lymphocytic infiltration of the ducts within the foci. The remaining changes were not specific for SS.

Plunging ranula--an unusual presentation

An unusual presentation of a plunging ranula is described which suggests that raised air pressures within the oral cavity may be an additional factor in its aetiology.

Ranula and sarcoid granuloma of a sublingual gland

A case is reported in which the treatment of the ranula consisted of dissection of the cystic wall along with excision of the sublingual gland of origin. The histological picture of the gland was consistent with sarcoidosis. Thereafter, all other examinations were negative for sarcoidosis. However, there remains the possibility that the lesion may be the precursor of widespread sarcoidosis which might occur in the future.

A new mutation involving the sublingual gland in NFS/N mice. Partially arrested mucous cell differentiation

A new mutation in mice affecting the mucous cell differentiation of the sublingual glands is described. The normal mouse sublingual glands are mucus-secreting and virtually all the acinar cells differentiate to mucus-rich cells by the day of birth. In contrast, all endpieces of newborn mutant mice consisted of acini of immature cuboidal cells. However, normal mucous cells, staining intensively with mucin-specific stains such as Alcian blue at pH 2.5 or mucicarmine, appeared in the mutant mice from an early age singly or in groups in a small number of acini, and their number apparently increased with age to occupy over 30% of the total acinar cells. Ultrastructurally, irregular secretion granules of varying electron-density, distinct from ordinary sublingual mucin granules, were frequently observed in the cytoplasm of the immature acinar cells in the mutant phenotype. The genetic analysis showed that a single autosomal recessive gene determined the observed abnormality. This is the first salivary gland mutation and will provide a critical model for the study of salivary mucous cell differentiation.

The effects of upper incisor separation on the submandibular and sublingual glands of rats

The effects of upper incisor separation on the submandibular and sublingual glands of rats were examined biochemically, immunohistologically, and radio-immunologically during 28 days of treatment. Lateral separation of the upper incisors by application of force from an orthodontic appliance caused significant enlargement of the sublingual and submandibular glands of rats by three and seven days, respectively, after the beginning of the orthodontic treatment. This enlargement was followed by a significant increase of both RNA and DNA content, with some evidence of hyperplasia and hypertrophy. The enlargement was also associated with a significant increase of substance P at early stages after treatment, suggesting the involvement of the sensory nerves. These changes were largely inhibited by phenoxybenzamine, an alpha-adrenergic blocker, but not by atropine or morphine. Wet weights and RNA contents of the sublingual glands were markedly reduced by atropine. In comparison with control animals, the enlarged submandibular glands of rats subjected to orthodontic treatment secreted additional proteins identical with those secreted by glands enlarged by chronic administration of isoproterenol. In addition, chemical sympathectomy with 6-hydroxydopamine and phenoxybenzamine stimulated the synthesis of these abnormal proteins, but atropine and morphine did not. In contrast, protease activities in the convoluted granular tubule cells in the submandibular glands were increasingly reduced after treatment, as seen in rats subjected to chronic treatment with isoproterenol. However, the submandibular and sublingual glands completely recovered after removal of the orthodontic appliance.

Salivary glands in long-term alloxan-diabetic rats. A quantitative light and electron-microscopic study

Fifty untreated diabetic animals were compared with 58 age-matched non-diabetic controls. Reduced salivary gland weight was evident after one month's diabetes and this was unchanged after 12 months of diabetes. Submandibular/sublingual gland weight was proportional to the reduced body weight in the diabetic rats. Parotid gland weight, however, was proportionally more reduced. Only diabetic rats had lipid inclusions in the acinar cells of their submandibular glands and the morphometrically estimated amount of inclusions was positively correlated to the blood glucose level. Acinar cell size was significantly increased in long-term diabetic rats as compared with short-term diabetic rats and controls. Capillary basement membrane width was significantly increased in long-term diabetic rats compared with age-matched controls and with short-term diabetic rats. Thus, both the degree and duration of diabetes have a major effect on salivary gland morphology in alloxan diabetic rats.

Granulomatous inflammation of minor salivary gland ducts: a new oral manifestation of Crohn's disease

Multiple sublingual cystic masses developed in a 27-year-old man with active intestinal Crohn's disease during prednisone therapy. Surgical excision revealed noncaseating granulomatous inflammation involving the walls of minor salivary gland ducts. In some areas, this ductal lesion was associated with rupture and mucocele formation. Three weeks after excision of the salivary gland tissue, the patient experienced an exacerbation of his intestinal disease, accompanied by a recurrent lesion on the floor of his mouth and aphthous ulcerations of the buccal mucosa. The oral lesions and intestinal symptoms resolved only after azathioprine therapy. This salivary gland lesion represents a previously undescribed oral manifestation of Crohn's disease.

Mylohyoid herniation: gross and histologic evaluation with clinical correlation

The purpose of this study was to further document the presence of a mass herniating inferiorly through the mylohyoid muscle into the submandibular area, to identify the mass histologically, and to discuss its importance in a differential diagnosis of masses in this area. A mass that perforated the mylohyoid muscle was found in 45 of the 100 cadavers studied. These 45 cadavers contained a total of 63 herniations. Of the 60 male cadavers, 26 (43.33%) showed herniation, and 19 (47.50%) of the 40 female cadavers showed herniation. Histologic evaluation of the 63 biopsy specimens revealed the following: 30 herniating masses (47.61%) were of the sublingual gland; 28 (44.44%) were of the submandibular gland; 4 (6.34%) were composed of pure adipose tissue, and 1 (1.58%) was a cholesteatoma. Inflammation was found in 46 (73.00%) of the biopsy specimens, consisting of sclerosing sialoadenitis in 30 specimens (47.61%) and a mild chronic inflammatory infiltrate in 16 specimens (25.39%).

[Sonographic detection of salivary calculi of the sublingual gland]

Ultrasound (US) proved highly effective for detection and localisation of stones in salivary glands. Because of the high accuracy and the possibility to detect non-opaque stones sonography should be performed as a supplementary measure if on plain film the localisation of the calculi is questionable. In this study we report on two patients with stones in the glandula sublingualis.

Cervical mucocele (plunging ranula): an unusual case of mucous extravasation cyst

An unusual case of a mucous extravasation cyst that manifest itself solely as a cervical swelling is reported. As a result of this unusual symptom, diagnosis and appropriate treatment were delayed, and the condition finally resolved after the ipsilateral sublingual salivary gland was excised and the cervical fluid was aspirated. Cervical mucoceles have also been reported in dogs, and the veterinary literature pertaining to this is briefly reviewed.

Spontaneous hyperplastic and metaplastic duct epithelium in the sublingual salivary glands of Wistar rats

Focal epithelial hyperplasia and metaplasia were observed in the intralobular ducts of the sublingual salivary glands of 302 out of 1142 Wistar rats. These rats (aged 16-145 weeks) served as controls in toxicological experiments. The ductal changes varied from small groups of irregular cylindrical cells with basophilic cytoplasm and vesicular nuclei, with often prominent nucleoli, to large areas of non-keratinized stratified squamous epithelium with marked mitotic activity and necrotic superficial cells being released in the lumen. Mononuclear inflammatory cells were often present in fibrous tissue surrounding altered ducts. Within certain limits the degree and incidence of the changes increased with increasing age; their aetiology is unknown.