Ultrastructure of the middle-ear mucosa in secretory otitis media. I. Serous effusion

Isolated malleus neck fracture

Isolated fracture of the malleus seems to be an extremely rare ossicular injury. All previously reported cases involved the handle of the malleus. This is the first reported case of fracture of the neck of the malleus. The diagnosis can easily be missed because the tympanic membrane remains intact. Furthermore, the history may not be suggestive. Surgical repair is particularly difficult.

IL-1beta promotes the ciliogenesis of human middle ear epithelial cells: possible linkage with the expression of mucin gene 8

CONCLUSIONS

These findings suggest that IL-1beta, increases ciliogenesis in NHMEE cells and that MUC8 protein may play a role in this process.

OBJECTIVES

The morphology of the middle ear epithelium changes under various pathologic conditions. We compared the density of ciliated cells and the level of mucin gene 8 (MUC8) mRNA in the middle ear epithelial cells of mucoid otitis media (MOM) patients with those of normal controls. We also investigated the effect of IL-1beta on the ciliogenesis and expression of MUC8 mRNA in cultured normal human middle ear epithelial (NHMEE) cells. In addition, we localized the MUC8 protein in cultured NHMEE cells.

MATERIAL AND METHODS

The surface morphology of NHMEE cells was examined using scanning electron microscopy. Reverse transcriptase polymerase chain reaction was performed to determine the level of MUC8 mRNA expression. After synthesis of MUC8 polyclonal antibody, we performed immunohistochemical staining.

RESULTS

The density of ciliated cells was increased in the middle ear epithelium of both MOM patients and IL-1beta-treated cultures. Similarly, the expression of MUC8 was increased in both cases. MUC8 antibody was primarily stained on the ciliated cells of NHMEE cells.

Surface morphology of middle ear epithelium in chronic ear disease

The ultrastructural details of normal middle ear mucosa have been reported in detail in the literature. This study was aimed at investigating the superficial structure of middle ear epithelium with the scanning electron microscope in patients with persistent otitis media with effusion (OME) and chronic suppurative otitis media (CSOM), especially in the light of the authors' recent findings regarding decreased ciliary beat frequency (CBF) in patients exposed to tobacco smoke. Mucosal biopsies were taken from the anterior mesotympanum in four patients with OME and another four patients with CSOM. There was no significant abnormality of cellular surface structure in patients with chronic middle ear disease. Furthermore, no significant difference was observed between smoke exposed and nonsmoke exposed patients. It is concluded that the effect of tobacco smoke on CBF is functional and not related to any anatomical abnormality observed by scanning electron microscopy (SEM).

Accuracy of an automatic impedance apparatus in a population with secretory otitis media: principles in the evaluation of tympanometrical findings

INTRODUCTION

The primary demand for a screening procedure for secretory otitis media (SOM) is to identify an objective test with sufficient sensitivity and specificity to meet the needs of the screening program. This study was designed to estimate the value of a portable automatic impedance apparatus to meet these needs.

SUBJECTS AND METHODS

Two hundred twenty children with unilateral or bilateral SOM were evaluated in a double-blind, cross-sectional study. All have fulfilled two of the following three criteria for surgical intervention: (1) SOM by physical examination, (2) greater than 20 dB hearing impairment, and/or (3) adenoid symptoms. All ears were evaluated using tympanometry, following which myringotomy was performed.

RESULTS

Otomicroscopy showed fluid behind the tympanic membrane in 393 ears. All underwent myringotomy. Thirteen percent (51 ears) were empty. Of the otomicroscopic findings consistent with SOM, 82% had B curves, 6% had C2 curves, 8% had C1 curves, and 4% had A curves. Both C2 and B curves were considered abnormal. Sensitivity of the apparatus is 94.4% and of the specificity is 52.9%. There was no statistical correlation between tympanometrical findings and fluid viscosity.

RESULTS

A test intended for screening has to be simple, easy, and quick to perform. Furthermore, the test should have high sensitivity. The automatic impedance apparatus is able to meet these demands; however, the individual results have to be confirmed by another method, eg, otomicroscopy, pure-tone audiometry, and/or manual tympanometry.

Superoxide dismutase in middle ear fluid from children with secretory otitis media

Superoxide dismutase (SOD) constitutes an important enzymatic defense against the destructive biochemical events associated with inflammation. To examine the presence of SOD in the middle ear fluid (MEF) in secretory otitis media (SOM) the content of SOD was measured in the MEF from 66 children with SOM. The applied method was based on light emission associated with reduction of the chemiluminescence of luminol reacting with superoxide anions (O2-). From the inhibition exerted by the addition of standard SOD the concentration of SOD in the samples was extrapolated. The findings divided the MEF's into two significantly different groups: 48% with undetectable SOD, 52% with a SOD range of 200-12,000 ng/ml, median: 3,333 ng/ml, 95% confidence limits: 2,000-5,000 ng/ml (p < 0.0005). It is suggested that the concentration of superoxide dismutase in the middle ear may play an essential role for the outcome of secretory otitis media and the effect of insertion of ventilation tubes.

Histological examination of the rabbit middle ear in secretory otitis media with and without a ventilation tube

To study the time-related histopathological lesions in secretory otitis media as it develops into the chronic stage, including the influence of ventilation of the middle ear, we examined the middle ear mucosa in a rabbit model. The observation period was from two weeks until 18 months. The histological method applied included haematoxylin-eosin and Sirius red staining for morphometric quantification of the goblet cells, the thickness of the connective tissue layer, the area fractions of blood vessels, inflammatory cells, fibroblasts and collagen fibres. In conclusion, the middle ear mucosa in secretory otitis media exhibited inflammatory changes correlating with the duration of the disease. Ventilation of the middle ear in secretory otitis media did not improve the changes.

Changes of middle ear mucosa in secretory otitis media treated with ventilation tubes

The present study was designed to obtain the precise ultrastructural status of the middle ear mucosa of patients to whom ventilation tubes were applied for the treatment of secretory otitis media (SOM). This study comprised 14 children with SOM aged 5-11. Normal epithelium obtained from otosclerotic patients as controls was composed of three main cell types; basal, ciliated, and secretory. Electron microscopic observations revealed that ciliated cells were almost completely absent in the epithelium of patients with SOM. Secretory cells, on the other hand, were noted to be increased in number with cytoplasmic features indicating active secretory phase; abundant secretory granules in these cells featured both serous and mucoid characteristics. Following the application of ventilation tubes, the micrographs exhibited a vast number of ciliated cells. Furthermore, the secretory cells were less conspicuous and the secretory granules were mostly serous in type. The ultrastructural findings of this investigation strongly suggest that the application of ventilation tubes in cases of SOM stimulates ciliated cell regeneration, inhibits secretion of mucoid material, and activates serous secretion; all of which eventually shorten the recovery period.

Experimental otitis media with effusion induced by intratympanic lipid A instillation

Otitis media with effusion was induced in guinea pigs by intratympanic instillation of lipid A, the lipid moiety of gram-negative bacterial lipopolysaccharide from Salmonella minnesota Re595. Lipid A was chosen as an inducer because of its similar composition among various bacterial species. Animals were killed from the first to 14th day after instillation of various concentrations (0.2, 2, 20, 200 micrograms/ml) of lipid A in 0.5% triethylamine. By 3 days after instillation, all experimental animals developed serous middle ear effusion. The histologic findings included hemorrhage, mucosal edema, capillary engorgement, and migration of infiltrative cells including macrophages, polymorphonuclear neutrophils, and lymphocytes. These findings were most prominent 3 days after instillation, and the recovery of the middle ear epithelium was observed within 14 days. Repeated instillation of lipid A (2 micrograms/ml) at an interval of 14 days reinforced the local response accompanied by serous middle ear effusion. These findings indicate that lipid A can induce the inflammatory changes with middle ear effusion and that lipid A plays an important role in the pathogenesis of otitis media with effusion.

Ultrastructural pathology of the middle ear mucosa in otitis media with effusion

To elucidate the histopathological features of the middle ear mucosa in otitis media with effusion (OME), 33 specimens were obtained from OME patients (28 from children and 5 from adults) at the time of the ventilation tube insertion, and examined by light- and electron-microscopy. The mucosa from both pediatric and adult OME patients with glue effusion consisted mostly of non-ciliated cells containing numerous low electron-dense granules with or without a core, and many macroapocrine sections were observed on the apical surface of the cells. The mucosa with mucoid effusion showed various secretory activity, but macroapocrine secretions were rarely found. The intercellular space was intact and the junctional complex was well preserved. In serous otitis cases, the epithelia consisted mostly of cuboid ciliated cells and non-ciliated cells without definite secretory activity. But the intercellular space became widened and the junctional complex was occasionally damaged, indicating that the epithelium was quite permeable. We concluded that there was no significant histopathological difference between the OME mucosa of children and that of adults, although the nature of the effusion was closely correlated with the morphological features of the epithelial linings.

Histopathology of otitis media with effusion. An electron microscopic study of human temporal bones

Ultrastructural studies of the middle ear mucosa appear to be of significant value in better understanding the pathology of otitis media with effusion (OME). Our present study was undertaken in order to take advantage of the use of electron microscopy in investigating all areas of the middle ear mucosa. Tissues studied were obtained from the fresh postmortem temporal bones of three patients with OME and terminal head and neck malignancies. In the mucoid type of effusion (cases 1 and 2), goblet cells were seen to proliferate and secretory activity was greatly enhanced. In contrast, there was no evidence of secretory cell proliferation in the serous type of effusion. It was noteworthy that accumulated fluid was not homogeneous in the same ear, as exemplified by case 1, in which both mucoid and serous effusions were present. This occurrence was possibly the result of topographic diversity involving the secretory activity of the middle ear.

Tympanosclerosis of the ear drum in secretory otitis media

Tympanosclerosis of the ear drum in children with SOM differs from normal ear drums in children with SOM. In tympanosclerosis the numbers of fibroblasts, fibrocytes and macrophages are increased in lamina propria and in the submucosa. The collagen microfibrils and procollagen filaments have increased in numbers with a partly disorganized pattern. Fibrolysis of microfibrils is conspicuous and hyaline degeneration appears in areas. Calcareous deposits are found scattered to a limited extent in lamina propria and in the submucosa. Profound calcification could only be found in children with tympanosclerosis coexisting with chronic perforation of the ear drum.

Sem studies of the inflammatory changes of the middle ear mucosa

Mucosal specimens of the middle ear from patients who had chronic otitis media were studied and compared with normal middle ear specimens using a scanning electron microscope. The epithelia in chronic otitis media were usually thick and those surface structures varied depending on the area in which the biopsy was taken. Moreover, the structure was not uniform even in the same specimen. Some areas showed a great number of secretory cells, while others demonstrated high population of ciliated cells. Areas with loss of the superficial layer were also observed in a few cases. There were less ciliated cells than we expected. They were not evenly distributed, except for the eustachian tube region. Morphologically, most of these ciliated cells seemed to be normal, and a few isolated atrophic ones were also observed. In cholesteatoma cases, squamous epithelia with desquamating, flat and keratinized cells were observed.

Deviation with increasing age in histologic appearance of submucosal glands in human eustachian tubes

74 tubal specimens from the temporal bones of 37 autopsy cases of various ages (8 fetuses, 12 children, 4 young adults, 36 middle-aged adults, and l4 elderly adults) were examined histologically to study the deviation with increasing age in the submucosal glands of Eustachian tube. The tubal glands consisted of acini (terminal secretory portions) and three duct systems (intercalated, striated and excretory ducts). Cytologically, they were of the mixed type with crescents. It was observed that the mucous acinar cells were predominant in children, as compared with the serous acinar cells. These latter increased prominently in middle age, accompanied by a decrease in the number of mucous cells. Among the elderly, both types of acinar cells decreased and tended to be atrophic. On the other hand, oncocytic changes of the ductal epithelia were discovered in the pharyngeal part of Eustachian tubes of subjects over 60 years old. These aging changes may play an important role in the pathophysiology of patency and excretory processes of the Eustachian tube.

Studies on the production of middle-ear effusion in the experimental animal

Middle-ear effusions have been produced following eustachian tube obstruction in guinea pigs. This was achieved by plugging the pharyngeal office of the tube by an atraumatic lateral transpalatal incision. General anaesthesia was used throughout the entire procedure. The presence of fluid in the middle-ear cavity was determined by observing: (a) The appearance of pallor of the drum. (b) Retraction of the tympanic membrane. (c) Cloudiness of the tympanic bullae on radiographs obtained at weekly intervals, confirmed by: (d) Subsequent myringotomy. Serial smears of the induced effusions showed an absence of chronic inflammatory cells except in the case of one animal which developed bacterial otitis media. The presence of secretory cells was demonstrated in the actual epithelial layer and lamina propria but no discrete glands were found. Squamous metaplasia of the lining of the middle-ear cleft was noted. The fluid from the tympanic cavity appeared watery, faintly turbid and non-mucoid, and resembled the serious type of effusion found in man.

Pathogenesis and pathology of chronic secretory otitis media

Secretory otitis media is divided into three stages, and the pathogenesis and pathology of each stage are described on the basis of quantitative histopathological studies. In the initial stage, ie, the period before accumulation of mucus in the middle ear, metaplasia causes a transformation of the mucosa into a secretory mucosa and mucous glands are formed. These processes are described in detail. In the secretory stage, which is the period with accumulation of mucus in the middle ear, an enormous increase was found in the density of goblet cells and the density of active mucous glands was large. In the degenerative stage, the production of secretion abates owing to degeneration of the glands. These become inactive, and the mucosa gradually normalizes. The normalization process is slow and runs through several turnover periods of the epithelium by means of a gradually decreasing rate in the division of the basal cells.

Middle ear mucosa in cleft palate children. A scanning electron microscopic study

Twenty-three promontory mucosal specimens from cleft palate children were studied by scanning electron microscope. Comparative studies were made, using light and transmission electron microscopy. The mucosal lining was pseudostratified columnar with microvilli, a few ciliated cells with secretory granules and numerous goblet cells. A few mucous glands, could be seen in certain areas. Microvilli with bulging tips and cilia with microknobs were common phenomena. The submucosa were inflamed, with leukocytes, macrophages, plasma cells and lymphocytes, indicating the presence of both cellular and humeral defence mechanisms.

Certain oxidative and hydrolytic enzymes in the middle ear effusion in serous otitis media

Activities of various oxidative (LDH, MDH) and hydrolytic (LAP, alkaline- and acid phosphatase, and lysozyme) enzymes in serous middle ear effusions (MEE) and serum from patients with serous otitis media were studied. The ratio of enzyme activity between MEE and serum (MEE/serum) was greater than one for all enzymes studied indicating a higher activity of these enzymes in MEE than in serum. These findings are consistent with a hypothesis suggesting the release of enzymes from inflammatory processes in the middle ear cavity. These enzymes presumably originate from 1) enzymes normally present in blood, 2) release of enzymes from inflamed middle ear mucosa, 3) release of enzymes from inflammatory cells present in the effusions.

Secretory otitis. Histopathology and goblet-cell density in the Eustachian tube and middle ear in children

The histological changes in the middle ear of four children with incipient or mild chronic secretory otitis are described. They consist in vascular dilatation and proliferation, round-cell infiltration, epithelial metaplasia into pseudostratified, columnar, ciliated epithelium posteriorly in the middle ear, formation of abnormal mucous tubular glands, and an increase in goblet-cell density in the osseous tube and middle ear. The causes of these changes were presumably long-lasting tubal occlusion due to a permanent nasogastric tube and protracted catarrhal diseases. The density of goblet cells was determined in various parts of the Eustachian tube and middle ear. The findings were analysed statistically and compared with the density in prematures and newborns, normal children, and normal adults. In the tympanic orifice and in the osseous Eustachian tube the goblet-cell density was greatly increased, whereas the increase in the middle ear varied individually, but was in conformity with the other findings. These cases illustrate that the histopathological changes in the middle-ear mucosa in secretory otitis must be regarded not only from a qualitative, but certainly also from a quantitative point of view.

Ultrastructure of the middle ear mucosa

Histologic studies of recent years have definitely concluded that the epithelium of the middle ear is a modified respiratory epithelium with ciliated and secretory cells, including goblet cells. These cells, like the ciliated cells, are developd from the basal cell and are just ordinary secretory cells completely filled with secretory granules. For different reasons it is postulated, that the dark secretory granules are prestages of the actual secretory product presenting as light granules and that dark and light granules do not represent different secretory capacities of the cell. The subepithelial layer which consists of loose connective tissue is a structure of just as great importance as the epithelial layer.

Cell renewal in the eustachian tube epithelium of guinea pigs

The turnover time of the epithelial cells of a normal eustachian tube was estimated in guinea pigs by means of lightmicroscopic autoradiography with thymidine-H3. The cell migration from the basal layer to the tubal lumen was chased by sacrificing the animals at different intervals after tnymidine-H administration. This study revealed that the generative cells were the basal cells in the tubal epithelium and that the different types of maturative cells in the epithelium have a different life span. The turnover time of non-ciliated secretory cells was about 145 hrs (about 6 days), while that of ciliated cells and goblet cells more than 6 days.

Functional morphology of the lining membrane of the middle ear and Eustachian tube: an overview

A large part of normal middle ear cavity and Eustachian tube is provided with a mucociliary transportation system which is considered the first line of defense of the middle ear. Secretory cells of the normal mucosa of the middle ear and the tube can be classified into three main types: mucous, mixed and dark granulated (or serous). This may mean that the secreta of the mucosa is biochemically diverse and/or in a dynamic state. The presence of immunoglobulin-producing plasma cells (IgA, IgG and IgM) and macrophages in the Eustachian tube and the middle ear mucosa supports the concept that the middle ear is protected by an immunologic defense system. Normal mucosal epithelial cells of the middle ear and the tube possess the ability to transport macromolecules by intact epithelial cells toward connective tissue layer where the macromolecules are either phagocytized by histiocytes or enter into capillary system. The macrophages of regional lymph nodes also picked up the macromolecules. Demonstration of lamellar substances similar to phospholipids in the secreta of the tube and middle ear mucosa of the guinea pig suggests the presence of auditory surface-active agent(s) (surfactant). Close association between secretory cells of the mucosa and acid phosphatase is demonstrated by cytochemical method. It is suggested that secretory enzymes such as lysozyme and acid phosphatase may be either produced or transported by secretory cells of the middle ear mucosa. These enzyme secretions are considered a part of the enzymatic defense system of the middle ear.

Production of mucus in the middle ear and Eustachian tube. Embryology, anatomy, and pathology of the mucous glands and goblet cells in the Eustachian tube and middle ear

On the basis of quantitative studies of the mucus elements in 144 temporal bones and more than 5,000 biopsies the mucus producing capacity of the mucosa in the middle ear and Eustachian tube under normal conditions as well as in acute and chronic middle ear diseases is reviewed. In completely normal middle ears there was a very low goblet cell density and no mucous glands. Production of mucus does take place, but it is very slight. In acute conditions the goblet cell density in the Eustachian tube and middle ear increases, and metaplastic changes of the mucosa may occur, with formation of subepithelial and intraepithelial mucous glands. In chronic diseases, such as secretory otitis, there is a high gland and goblet cell density, which explains the increased production of mucus. In adhesive otitis the gland density is great, it is true, but most glands have become inactive and have degenerated. In chronic suppurative otitis, cholesteatoma, and sequelae to chronic otitis the goblet cell and gland density is moderately increased, but there are very marked individual variations which explain the great difference in the production of mucus. In active chronic diseases the mucus elements may increase enormously, and the mucus producing capacity of the epithelium may reach the heights of that of the respiratory mucosa.