Immunohistochemical observations on carbonic anhydrase I and II in human salivary glands and submandibular obstructive adenitis

Immunohistochemical identification of carbonic anhydrase I and II (CA-I, CA-II) was made in human major salivary glands and obstructive adenitis in submandibular glands. Normal salivary glands stained the strongest for CA-II in serious acinar cells and were negative in mucous cells. Moderate to strong staining for CA-I and CA-II was found in ductal segments. Submandibular glands with obstructive adenitis exhibited reduced CA-I activity in atrophic acinar cells, but not in ductal elements in the early and intermediate stages of the disorder. In the late stage of the obstructive lesion, CA staining in duct-like structures was moderate; however, almost degenerate ductal cells were negative for CA. During the progression of the degeneration in the obstructive lesion, the CA staining decreased dependent on acinar atrophy. Even after longstanding obstruction of the salivary gland, altered ductal epithelia may retain some of their functions.     

Immunohistochemical observations on carbonic anhydrase I and II in human salivary glands and submandibular obstructive adenitis

Abstract Immunohistochemical identification of carbonic anhydrase I and II (CA-I, CA-II) was made in human major salivary glands and obstructive adenitis in submandibular glands. Normal salivary glands stained the strongest for CA-II in serous acinar cells and were negative in mucous cells. Moderate to strong staining for CA-I and CA-II was found in ductal segments. Submandibular glands with obstructive adenitis exhibited reduced CA-1 activity in atrophic acinar cells, but not in ductal elements in the early and intermediate stages of the disorder. In the late stage of the obstructive lesion, CA staining in duct-like structures was moderate; however, almost degenerate ductal cells were negative for CA. During the progression of the degeneration in the obstructive lesion, the CA staining decreased dependent on acinar atrophy. Even after longstanding obstruction of the salivary gland, altered ductal epithelia may retain some of their functions.     

Acceleration of rat salivary gland tissue repair by basic fibroblast growth factor

A model of atrophic rat submandibular gland was used to examine the ability of basic fibroblast growth factor (bFGF) to accelerate tissue repair. The gland duct was separated carefully from associated blood vessels and nerve, and ligated with a 8-0 suture under a surgical microscope. Two weeks after ligation, the glandular tissue showed severe atrophy and weight loss (to 26% of that in a sham-operated group). Thereafter, the ligature was removed and various amounts of bFGF, isoproterenol or saline were instilled retrogradely through the duct. Both isoproterenol and bFGF increased cell proliferation significantly. bFGF accelerated the proliferation of various cell types, including both acinar and ductal. The proliferative effects of bFGF peaked at a dose of 1 ng/gland. When bFGF (1 ng/gland) was administered to the atrophic gland, its weight increased to 125% of the glands in saline-treated control animals after 2 weeks. The effects of bFGF were also examined in normal submandibular glands: bFGF stimulated cell proliferation, but the effective concentration was at least 50 times higher than that required in the atrophic gland. The results from immunohistochemical tests against anti-FGF receptor-type 1 antibody demonstrated increased immunoreactivity in the damaged gland, which might be involved in the difference in the response to bFGF between damaged and normal glands. Overall, the results indicate that bFGF can accelerate tissue repair in salivary gland.     

Ossification of the petrotympanic fissure: morphological analysis and clinical implications

The petrotympanic fissure, a narrow slit in the temporal bone, allows the temporomandibular joint (TMJ) and the middle ear to communicate. Both the chorda tympani and the ligament cross the fissure between the posterior region of the joint disk and the malleolar ossicle. The parasympathetic fibers of the chorda tympani spread into the major salivary glands and are responsible for the taste sensibility on the anterior two-thirds of the tongue. After chronological identification of 30 human skulls, petrotympanic fissures were macroscopically and stereomicroscopically analyzed for the presence and disposition of ossification areas. Digitalized images were analyzed using computer program UTHSCSA ImageTool 3.0 (developed by the Department of Dental Diagnostic Science at The University of Texas Health Science Center, San Antonio, Texas). The total extension of the fissures and ossification areas was measured. The macroscopic analysis did not constitute an appropriated method for this evaluation and the ossification of the fissures increased with aging, suggesting its influence on the causes of otalgia in cases of TMJ dysfunction.     

Expression of collagen and elastic fibers in duct-ligated submandibular glands of mice

Atrophy of salivary glands may occur by ductal obstruction caused by calculus, infection or neoplastic processes, or as consequence of systemic diseases and aging. In the present work, we have used histochemical methods to study the expression of elastic and collagen fibers during experimental atrophy of the submandibular gland of mice. Glandular atrophy was accompanied by a rapid increase in collagen deposition in both septal and intralobular regions. The expression of elastic fibers was not significantly altered during atrophy; a discrete increase of elastic fibers was noted only around ductal structures. The results showed that experimental ductal obstruction is a useful in vivo model to study molecular events that take part in the remodeling of the extracellular matrix during atrophy of salivary glands.     

Structural and functional injury in minipig salivary glands following fractionated exposure to 70 Gy of ionizing radiation: an animal model for human radiation-induced salivary gland injury

This study explored the feasibility of developing an animal model for radiation-induced salivary gland injury with a radiation protocol identical to current clinical practice. Three male Hanford minipigs were subjected to fractionated daily irradiation with a total dose of 70 Gy; structural and functional measures were compared with those of a control group of minipigs. We found that irradiated submandibular and parotid glands were one-third to one-half the gross size of control glands. Whereas no pathologic changes were noted in control glands, irradiated glands consistently demonstrated significant parenchymal loss with extensive acinar atrophy and interstitial fibrosis, enlarged nuclei in remaining acinar cells, and ductal dilatation and proliferation. Stimulated salivary flow was reduced by 81% in irradiated animals compared with preirradiation flow (P <.001); salivary flow in the control group increased by 30% during the same period (P <.001). The observed radiation-induced structural and functional salivary gland changes are comparable in every respect to those observed following irradiation of human salivary glands.     

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.     

Secretory activity and the myoepithelial cells of salivary glands after duct ligation in cats

Submandibular and parotid ducts were tied unilaterally in cats for periods from 12 to 81 days. Secretion has been tested in the glands on supramaximal nerve stimulation. Duct ligation caused a large reduction in secretory capacity but a small amount of secretion could always be obtained, even from very atrophic glands. Pressure changes were tested in the ducts resulting from nerve stimulation and from certain drugs administered intravenously. Responses attributable to myoepithelial contraction, which could be distinguished from secretion, were found on parasympathetic nerve stimulation, with parasympathomimetic drugs and also with kallidin and bradykinin. An increased sensitivity to the kinins was found in ligated glands.Histological and ultrastructural studies showed that the extent of the acinar atrophy paralleled the diminution in secretion. Myoepithelial cells persisted, but often showed an abnormal architecture, especially where underlying acinar atrophy had occurred, and in such sites they were associated with a grossly thickened basement membrane. The work supports the concept that salivary myoepithelial cells in the cat have a motor parasympathetic innervation.     

Morphological and functional characteristics of acinar atrophy and recovery in the duct-ligated parotid gland of the rat

Although acinar atrophy occurs frequently in salivary diseases, the relationship between structural changes and functional decrements is not well-established, and the potential for recovery of histological and functional integrity has not been wholly quantified. We aimed, therefore, to develop further our understanding of pathological acinar atrophy. Stensen's duct was ligated for periods up to six weeks and, in separate experiments, was de-ligated after two weeks and allowed to recover for up to two weeks. Qualitative and quantitative histological analyses were carried out. Additionally, the ability of enzymatically dispersed cells from ligated and de-ligated glands to respond to neurohormonal stimuli was also measured. The results confirmed that totally obstructed glands undergo a rapid, progressive severe atrophy amounting to absolute losses of over 85% of acinar tissue by two weeks. Acinar shrinkage and cell losses through apoptosis accounted for the glandular atrophy. Remaining intralobular epithelia consisted of extremely atrophic acini and numerous duct-like structures with intermediate forms. Dispersed cells from atrophic glands exhibited agonist-induced release of chloride similar to normal. Together, these structural-functional results confirm the persistent viability of acinar-like cells in the obstructed gland and suggest that the duct-like structures are derived from surviving atrophic acini. De-ligated glands exhibited a near-normal recovery of structure by two weeks. Their enzymatically dispersed cells responded normally to agonist stimulation. The results support the view that pathological atrophy is largely similar to physiological atrophy, providing a mechanism for acinar cell survival under adverse conditions, with the possibility of eventual recovery.     

A qualitative and quantitative study of the ageing human labial salivary glands

A series of 36 post-mortem labial salivary glands from both male and female subjects with ages ranging from 25 to 80 yr were examined histologically. Features such as acinar atrophy, fibrous replacement and ductal aberrations were noted in the aged glands. By the stereological method of point counting, the volume proportions of various defined gland constituents were calculated for individual glands in the series. An age-related decrease in acinar volume proportion and an increase in ductal and connective tissue volume proportion is recorded. These changes should be considered when diseased glands are studied.     

Responses of salivary glands to intake of soft diet

BackgroundModernization has made individuals prefer processed and cooked foods (soft food), but this eating habit may have negative effects on the oral cavity. However, laboratory animals fed with soft diet are commonly used in an attempt to clarify this issue, and various oral tissues, including the salivary glands have been examined. In this review, we summarize the findings of previous studies concerning the responses of salivary glands to daily intake of soft diet.HighlightThe weight of the parotid glands decreased in rodents fed with soft diet (liquid or powder). In atrophic parotid glands, acinar cell shrinkage is histologically observed and the DNA content is reduced, showing that the atrophy is caused by a decrease in the size and number of acinar cells. Immunohistochemical examinations showed that the decrease in the acinar cell number was induced by suppression of acinar cell proliferation and acceleration of apoptosis. The atrophic parotid glands recovered following a change from soft to pellet diet. Other salivary glands, such as the submandibular, sublingual, and palatine glands, responded only slightly to the soft diet feeding.ConclusionAccumulated research data showed that a soft diet negatively affects the parotid glands much more than other salivary glands and that atrophic parotid glands are able to recover by switching to a hard diet. Therefore, it should be emphasized that good eating habits are important for not only digestion but also the health of oral tissues, including the salivary glands.     

Histochemical studies of obstructive adenitis in human submandibular salivary glands. II. Lectin binding and keratin distribution in the lesions

Lectin-binding profiles and keratin distribution in obstructive adenitis of human submandibular glands (SMGs) are reported and compared those of normal SMGs. Histologically, obstructive changes in the SMGs included acinar atrophy, duct-like structure formation in the early stage, and disappearance of acinar cells and dilation of ductal segments in the later, chronic stage. The following lectins were used: Con A (Glc, Man), PNA(Gal, GalNAc), RCA-I(Gal), DBA(GalNAc), SBA(Gal, Gal-NAc), UEA-I(alpha-L-Fuc) and WGA(GlcNAC, NeuNAc). Lectin staining in atrophic acinar cells was usually reduced except for SBA binding and was irregularly distributed in altered acinar and ductal epithelia. Binding of DBA and UEA-I lectins were particularly intense along the luminar borders of ductal segments in the lesions. Immunohistochemically detectable keratins were characterized by intense staining in atrophic acinar cells and in all the ductal segments, whereas normal acinar cells, either serous or mucous, were negative.     

Cell population changes during atrophy and regeneration of rat parotid gland

Limited data exist regarding the changes in number and location of myoepithelial cells during salivary gland atrophy and regeneration. Through the use of double immunohistochemical labeling for muscle-specific actin and amylase coupled with morphometric analysis, this study investigated the changes in distribution and proportion of cell types during salivary gland atrophy/regeneration phases in a model previously used to study proliferation in rat parotid gland. The double immunohistochemical labeling clearly showed the changes in proportion of cell types in the atrophying and regenerating glands. The morphometric analysis showed that the relative myoepithelial area increased (as did the intercalated duct and striated duct areas) as the gland atrophied. Myoepithelial cells occupied 19.0% of the total epithelial area by day 7 of atrophy, up from 2.7% in the resting gland. Regeneration of acinar cells was obvious 1 day after duct release. The myoepithelial cell area decreased to 4.3% of the total epithelial area by day 14 of regeneration; this value was higher than the percentage of area in the resting gland (p = 0.02). The relative areas of acinar, striated duct, and intercalated duct cells returned to resting levels after 14 days of regeneration. The morphometric and histologic results of this study show that the parotid gland is capable of regenerating to essentially normal anatomic condition after 7 days of gland atrophy and then 14 days of regeneration. Each type of cell, however, responded to the atrophy and regeneration differently. Atrophy of salivary glands from radiation therapy, Sjögren's syndrome, or sialadenitis is an important clinical problem. Study of the salivary gland response to atrophy and regeneration may provide a framework for designing strategies for the radioprotection of salivary glands or methods by which to treat or reverse the effects of gland atrophy.     

Ultrastructural localization of microliths in salivary glands of cat

Although microliths occur in normal human salivary glands and may be an aetiological factor of sialadenitis, little is known of their natural history. In an attempt to remedy this, we investigated a large archival collection of normal and experimental feline parotid, submandibular and sublingual salivary glands. In submandibular and sublingual glands, microliths were detected ultrastructurally in: all types of acinar secretory cells; myoepithelial cells; ductal cells; lumina; intercellular spaces; basement membrane; stroma; macrophages; multinuclear giant cells; and neutrophils. Microliths were not detected ultrastructurally in parotid glands. Microliths appear to form in acinar cells during autophagy and in stagnant secretory material in lumina. Microliths appear to be removed by secretion in the saliva, discharge from cells laterally and basally, and engulfment by macrophages. There appears to be a turnover of microliths, which possibly is upset by secretory inactivity with a resulting accumulation that leads to localized obstruction and sialadenitis.     

Transplantation of vascularized submandibular gland in dogs.

PURPOSE: Presently, treatments for xerostomia only target symptoms, as an active therapy method has not been established. Herein, we discuss the possibility of using a submandibular gland allograft technique for the disease. MATERIALS AND METHODS: Using a vascularized submandibular gland transplantation method, we extracted portions of the submandibular gland, including the duct and chorda tympani branches, from beagle dogs and placed them into the submental region of age- and weight-matched dogs. We then measured the amount of saliva secretion and examined the grafted glands histologically. RESULTS: Sufficient quantities of saliva were secreted from the grafted glands with pilocarpine treatment. Histologic findings showed that the acinar cells in the grafted and untreated contralateral glands had some atrophy, as compared with the normal glands; however, periodic acid Schiff staining showed that they produced saliva. CONCLUSIONS: Transplantation of vascularized submandibular glands into dogs was successful and may become a novel treatment strategy for patients with xerostomia.     

Unusual variant of chorda tympani syndrome, its management, and a proposal on the nervous pathways involved

Chorda tympani syndrome is an uncommon condition with similarities to Frey syndrome. We describe a variant of chorda tympani syndrome and its management, and put forward a hypothesis for the nervous pathways involved; something that seems to be lacking in published material.     

An electrophysiological study into the effect of neurotrophin-3 on functional recovery after lingual nerve repair

OBJECTIVE: Neurotrophin-3 (NT-3) is known to ameliorate central changes that result from peripheral nerve injury and may promote regeneration of myelinated axons. We have assessed its role in the functional recovery of sensory afferents and autonomic efferents after repair of the chorda tympani and lingual nerves in the cat. DESIGN: Six months after entubulation repair, with or without the incorporation of NT-3 at the repair site, the recovery of secretomotor and vasomotor efferents was determined by recording salivary flow from the submandibular gland and temperature changes on the tongue surface, each evoked by stimulation of the repaired nerve. Electrophysiological recordings from the lingual and chorda tympani nerves proximal to the repair allowed characterisation of mechanosensitive, thermosensitive and gustatory afferents. RESULTS: When compared with data from uninjured control animals, both repair groups showed persistent reductions in conduction velocity, receptor sensitivity, spontaneous discharge, proportion of gustatory and thermosensitive units, and rate of salivary secretion. Comparisons between the two repair groups revealed that in the NT-3 group, salivary secretion rate was lower and the activity evoked in the chorda tympani by gustatory or thermal stimuli was lower, but the spontaneous discharge rate was higher. Mechanosensitive units in the lingual nerve had slower conduction velocities but the mechanoreceptive field size, adaptation time and discharge frequency had increased. CONCLUSIONS: Despite its known trophic role in the lingual somatosensory system, NT-3 did not enhance functional recovery from injury and had a negative effect on the long-term outcome for sensory and autonomic fibres.     

Surgery of the salivary ducts

Successful surgery of the salivary ducts relies on an understanding of the surrounding anatomy and the delicate dissection of tissues in order to reduce morbidity. Trauma to the ducts should be assessed when lacerations or wounds encroach on their paths. Early diagnosis and treatment will reduce the complications of stricture and fistula formation from these injuries. Sialoliths can be located in several places along the length of the salivary ducts. The correct diagnosis and positioning of the stone in the duct is important in establishing the appropriate surgical approach. Imaging using plain films, ultrasonography, and endoscopy can be very valuable, with sialography and CT scans helpful in cases of radiolucent stones, glandular atrophy, or suspected tumor. As the condition becomes more chronic, resulting in glandular atrophy, excision of the diseased gland is often indicated. Treatment of excessive salivary flow in patients with cerebral palsy can be managed by a combination of ductal repositioning and glandular excision. Redirection of both the parotid and submandibular glands can be accomplished, either to reroute excess salivary flow or salvage the duct in cases of lesion excision.     

Immunoreaction of keratin, actin, S-100 protein and rat-EGF in ductligated 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.