Tympanic Orifice Research Articles

Appearance of effusion material in the attic space correlated to an impaired Eustachian tube function.

In adult Sprague-Dawley rats a dysfunction or a total blockade of the Eustachian tube was established by various experimental procedures. The appearance of effusion material in the attic was subsequently considered to be evidence of incomplete ventilation of the middle ear cavity. Though the salpingopharyngeus muscle (SPM) seemed to be the muscle which could open the Eustachian tube maximally, splitting of the soft palate and consequent interference with the tensor veli palatini muscle (TVPM) and the levator veli palatini muscle (LVPM)--but obviously not with the salpingopharyngeus muscle (SPM)--caused the effusion material to be produced in the middle ear cavity. Neither blockade by about 80% of the tympanal orifice nor severing of the tendon of the tensor tympani muscle (TTM) close to the malleus produced any signs of effusion material whatsoever. Our findings strongly suggest that the most important part of the Eustachian tube, as regards ventilation, is the nasopharyngeal portion, as a normally functioning TVPM and LVPM seems to be an absolute prerequisite to prevent effusion material from developing in the attic.

The anatomy of the eustachian tube in the rat: a macro- and microscopical study.

The rat eustachian tube (ET), from the nasopharyngeal orifice to the tympanal orifice, is about 4.5 mm long, of which the naso-medial membranous part (the nasopharyngeal orifice) measures about 1.5 mm and the occipito-lateral bony portion about 3 mm. The nasopharyngeal orifice is surrounded by two soft, lip-like, mucosal swellings--one ventral and one cranial--both easily mobile. The muscles related to the tubal opening mechanisms are the salpingopharyngeus, the tensor veli palatini and the levator veli palatini muscles. The salpingopharyngeus muscle originates partly from the cranial lip, whereas the palatal muscles originate partly from the ventral lip. The tympanal two thirds of the mucosal lining of the ET is cranially guided by a cartilage and incompletely framed by bony structures. The tympanal orifice is situated in the nasal part of the medial wall, well above the floor of the bulla. The tensor tympani muscle does not seem to take part in the opening and closing mechanisms of the ET. The mucosal lining of the ET consists of a respiratory epithelium with numerous glands in the lamina propria. It is suggested that the tubal muscles control the passage through the ET by moving the lip-like folds of the nasopharyngeal orifice. The anatomy of the rat ET is comparable to that described in Homo and it can be concluded that the rat ET might be a good model for studying the function of the human ET.

The fine surface view of the human adult eustachian tube.

The distribution pattern of ciliated cells and goblet cells in the mucosa of the normal adult human eustachian tube has been determined by means of SEM. In general, the density of the ciliated cells decreased from the pharyngeal to the tympanic orifice, and from the tubal floor to its roof. Most ciliated cells possessed about 100-200 cilia, and the average length of the cilia was approximately 8 mu. It is interesting to note that their number and length had a tendency to diminish towards the tympanic orifice of the tube. The ciliated epithelial cells at the tubal floor and lower parts of the walls undoubtedly play an important part in providing an active mucociliary mechanism, as in other parts of the upper respiratory system.

Absorbable gelatin sponge (Gelfoam) in otosurgery: one cause of undesirable postoperative results?

Absorbable gelatin sponge (Gelfoam)--commonly used in otosurgery--was gently inserted or firmly packed into the middle ear cavities of rats. The postoperative changes were evaluated 2 to 3 months later when, apart from some air-filled canals leading from the tympanal orifice of the Eustachian tube towards the attic, the middle ear cavity had become filled with newly formed bone and an amorphous mass of adhesions and bridles. The mass consisted of loose connective tissue, with fibroblasts, vessels and inflammatory cells. The tympanic membrane was retracted and fixed to the promontory. There were no signs that any Gelfoam had been removed through the Eustachian tube. The authors proposed that similar tissue reactions may occur in tympano-plasties.

Morphological Study of Middle Ear and Eustachian Tube Part-one

Mucosa of the middle ear and the Eustachian tube were studied by the scanning electron microscope (SEM) in humans, dogs, rabbits and guinea pigs. The following results were obtained:1. Ciliated cells surrounded by nonciliated cells with microvilli were very few on the mucous of the middle ear. Distribution of ciliated cells was very various at the site of the tympanic bulla.2. Near the tympanic orifice of the Eustachian tube, less ciliated cells and numerous goblet cells were observed.3. The middle portion of the tube was found to be the most active. It was here that goblet cells and a large number of ciliated cells were found. Cilia were dense, uniform bent toward the pharyngeal end, and covered by a mucous blanket.4. Near the pharyngeal end, goblet cells were numerous, while cilia were scanty and not uniform in length.5. No significant difference could be seen among the four materials (humans, dogs, rabbits, guinea pigs).Our findings support the concept that middle ear clearance is carried out by an active mucociliary mechanism as in other parts of the upper respiratory system.

Fine structures of the normal mucosa in developing rat middle ear.

Forty-two fetal and 90 developing young rats were studied electron microscopically to obtain a normal cellular distribution pattern of middle ear mucosa. The results showed that while ciliated columnar or cuboidal cells interspersed with secretory cells were predominantly distributed around the tympanic orifice and transitional zone, cuboidal or squamous nonciliated cells without secretory granules were numerous in the remaining part of the bulla. Development of ciliated cells started at the 17th or 18 th fetal day,paralleling that of secretory cells. The number of ciliated and secretory cells increased rapidly after birth. Glands were not found in the osseous tube, tympanic orifice, or other portions of the middle ear cavity in fetal, newborn, or suckling rats, while they are abundant in the cartilaginous portion of the tube. The findings of this study indicate that both secretory and ciliated cells are normal components of middle ear mucosa although these cells are restricted to the tympanic orifice and transitional zone, and that the mucociliary defense system starts to develop during the fetal stage.

Fine structure of the epithelium in developing rat middle ear (author's transl)

Middle ear mucosae of 56 fetal and 90 young rats were investigated with SEM, TEM andserial sections for light microscope for the purpose of obtaining a better understanding of the fine structure of middle ear mucosa.The results of this study showed that secretory cells interspersed with ciliated cells were predominantly distributed around the tympanic orifice and transitionl zone.In general, the cellular distribution pattern between suckling rats and adult rats was similar, even though the distribution of ciliated and secretory cells varied to a certain extent from one adult to another.It was also evidenced that(1) light and dark secretory granules appeared in the Golgi area of some epithelial cells in 17 to 20 fetal day and that(2) primary cilla and immature cilia were seen from 16 to 17 fetal day in the transitional zone near the tympanic orifice.The number of ciliated and secretory cells increased rapidly after birth.It was failed to find glands in the osseous tube, tympanic orifice and other portion of the middle ear cavity in fetal, newborn and suckling rats, while there existed abundant glands in the cartilaginous portion of the tube.Secretory modes of Kurosumi's extrusion type II, 111, IV and V could be observed.The most common secretory cells were mucous cells with light secretory granules, showing eccrine secretion(type IV).The less common cells were the mixed granulated cells with apocrine secretion(type II and III).The liest was the dark granulated cells with eccrine secretion(type V).The distinction between light granulated and dark granulated cells was able to establish at 20 fetal day.Findings of this study indicate that both secretory and ciliated cells are normal components of middle ear mucosa although these cells are restricted within the tympanic orifice and transitional zone, and that the mucociliary defense system starts to develop at the fetal stage

The harp seal, Pagophilus groenlandicus, (Erxleben 1777). XIV. The gross and microscopic structure of the middle ear

The large, heavy ossicles of Pagophilus groenlandicus are firmly attached to the epitympanic wall by a single fold of epitympanic mucosa. The epithelium of the middle ear mucosa is pseudostratified columnar epithelium. Large cavernous sinuses are present below the dense collagenous fibers of the submucosa. The cavernous sinuses are prominent around the promontory and the medial wall of the tympanic orifice of the auditory tube, and also in the tympanic sulcus of the tympanic membrane. The distension of the cavernous tissue may aid in hearing.The wall of the auditory tube consists of thick collagenous and elastic fibers. The medial wall is a thick fibrous block of connective tissue. Hyaline cartilage forms the central core of the thick fibrous medial wall of the auditory tube. The robust wall of the tube makes it unlikely that the tube wall is collapsed by the increase pressure in the nasopharynx during diving. Pressure equilibration during diving may be achieved by the opening of the nasopharyngeal orifice by muscular contraction. The closing of the tube may be achieved by the elasticity in the tube wall.

Distribution and density of goblet cells in the normal adult human middle ear.

The purpose of this study was to map the distribution and density of goblet cells in the clinically normal middle ear. From 12 temporal bones, derived from 12 adult patients with clinically normal middle ears, the mucosa was prepared and stained by the PAS-alcian blue whole-mount method. In six of the patients the middle ears with meticulous gross and microscopic investigation showed mild sequelae of previous otitis media, called the slightly abnormal series, whereas the other six patients who had entirely normal middle ears were designated the normal series. Each middle ear was investigated in 12 different areas: tympanic orifice, hypotympanum anteriorly and posteriorly, round window niche, oval window niche, promontory anteriorly, in the middle, and posteriorly, epitympanum, antrum, and mastoid process. In each middle ear area the goblet-cell density and distribution were determined on the basis of 30 to 50 counts of 0.01768 mm2 epithelial surface, a total of at least 4800 counts. In six patients goblet cells were found in all 12 areas, in three patients in 11, and in three patients in 10. In both series there was a distinct decrease in goblet-cell density from the tympanic orifice, towards the posterior areas of the middle ear and the mastoid process. However, two patients of the slightly abnormal series exhibited a considerably greater density in the posterior than in the anterior part of the hypotympanum. The mean goblet-cell density in the slightly abnormal series was distinctly greater in all middle ear areas than in the normal series. Correspondingly, goblet cells were demonstrated in the antrum and mastoid process in all patients of the slightly abnormal series, but in only half of the normal series. Therefore, the greater goblet-cell density in the slightly abnormal series presumaby results from a previous past disease condition of the middle ear.

Density of goblet cells in the human Eustachian tube. Relationship between goblet-cell density in the tube and number of mucous glands in the middle ear.

In 14 temporal bones the mucosa from the Eustachian tube and middle ear was removed and stained by the PAS-alcian blue whole-mount method. The goblet-cell density in various parts of the tube was determined on the basis of 4 140 counts of 0.01768 mm counting fields. The number and density of glands in the entire middle ear and in its various parts were determined. In the normal series this revealed up to 50 glands (mean, 13 glands) with a mean density of 0.04 gland per mm2. In the slightly abnormal series there were 50-440 glands (mean 193) with a mean density of 0.85 gland per mm3. The goblet-cell density in the osseous part of the tube and in the tubal orifice was found to be considerably lower in the normal than in the slightly abnormal series. The density pattern of the goblet cells exhibited in the normal series a very marked and regular decrease into the tympanic direction and a very low density in the tympanic orifice. In the slightly abnormal series there was a moderate decrease of density into th...

Goblet cells in the human fetal eustachian tube.

Specimens from fetuses, premature infants, and a newborn were studied with special stain to elucidate the development of goblet cells in the eustachian tube and middle ear. It was found that development of goblet cells starts in the 12th menstrual week in the lateral wall of the rhinopharynx and spreads to the tube. Later, the goblet cells spread from Rosenmuller's fossa to the median wall, and goblet cell formation begins in the lateral wall in the 15th week. The development of goblet cells continues towards the tympanic orifice. In the second half of pregnancy, the number of goblet cells increases, and differences in density are gradually equalized. At birth the goblet cells are equally distributed throughout the tube; however, their density is greater in the pharyngeal than in the tympanic half. Goblet cells are present in the tympanic orifice, and may be seen in the anterior half of the hypotympanum and mesotympanum close to the orifice, but none in the other parts of the middle ear.

TOTAL TYMPANOPLASTY TYPE V. EUSTACHIAN TUBE PATENCY IN TYMPANOPLASTY.

The Introduction THE possibility of restoration of hearing in cases requiring a radical mastoidectomy is worthy of consideration when the eustachian tube remains patent, and there is bilateral conductive deafness. The removal of severe middle ear disease requires complete reepithelialization of the middle ear, the reconstruction of a new eardrum, and the reconstruction of a new conductive mechanism. Spontaneous reepithelialization of the middle ear occurs around Rambo's 1-4 paraffin implant; such spontaneous reepithelialization from the mucosal-lined tympanic orifice of the patent eustachian tube has given beautiful mucosal-lined middle ears as compared to disappointment with epithelial grafts to recreate a middle ear cavity. The reconstruction of the new eardrum, with a sandwich graft with an internal layer of temporal fascia and external layer of canal skin, has been almost uniformly successful, through a double coverage to all margins and the added internal vascularity preventing delayed central necrosis. This almost uniform success