Localization of efferent neurotransmitters in the inner ear of the homozygous Bronx waltzer mutant mouse.

Naturally occurring mutant mice provide an excellent model for the study of genetic malformations of the inner ear. Mice homozygous for the Bronx waltzer (bv/bv) mutation are severely hearing impaired or deaf and exhibit a 'waltzing' gait. Functional aspects of cochlear and vestibular efferents in the bv/bv mutant mouse are not well known. The present study was designed to evaluate several candidates of efferent neurotransmitters or neuromodulators including choline acetyltransferase (ChAT), gamma-aminobutyric acid (GABA), and calcitonin gene-related peptide (CGRP) in the inner ear of the bv/bv mutant mouse. Ultrastructural investigations at both light and electron microscopic level were performed. Ultrastructural morphologic evaluations of the cochlea and the vestibular end-organs were also undertaken. It is demonstrated that ChAT, GABA and CGRP immunoreactivities are present in the cochlea and in vestibular end-organs of bv/bv mutant mice. In the organ of Corti, immunoreactivity of ChAT, GABA and CGRP is confined to the inner spiral fibers, tunnel-crossing fibers, and the vesiculated nerve endings synapsing with outer hair cells. Interestingly, immunoreactivity was detectable even where inner hair cells appeared missing. Results also revealed malformations of the outer hair cells with synaptic contacts to efferent nerve endings consistently intact. In the neurosensory epithelia of the vestibular end-organs, the presence of ChAT, GABA, and CGRP immunoreactivity was localized at the vestibular efferents, with the exception of the macula of saccule. In one 8-month-old macula of utricle where the depletion of hair cells appeared highest, ChAT immunostaining was still discernible. Ultrastructural investigation demonstrated that vesiculated efferent nerve endings make synaptic contact with the outer hair cells in the organ of Corti and with type II hair cells in the vestibular end-organs. The present study provides further support that the efferent system in the bv/bv mutant inner ear is morphologically as well as functionally mature. These findings also demonstrate that if and when the onset of efferent degeneration in the bv/bv mutant inner ear occurs, it transpires subsequent to pathological conditions in the hair cells. The present findings give further indication that the efferent systems of the bv/bv mutant inner ear are independent of the afferent systems in many aspects including development, maturation as well as degeneration.

Goldenhar's syndrome: congenital hearing deficit of conductive or sensorineural origin? Temporal bone histopathologic study.

BACKGROUND: Oculoauriculovertebral dysplasia (OAVD) (Goldenhar's syndrome) is a congenital syndrome with ipsilateral deformity of the ear and face, epibulbar lipodermoids, coloboma, and vertebral anomalies. Goldenhar's anomaly has often been associated with a degree of congenital hearing deficits, almost always of a conductive origin, but a sensorineural component is also suspected in some cases, evident through malformations of the inner ear. PATIENTS AND METHODS: Both temporal bones of a 10-day-old deceased patient with oculoauriculovertebral dysplasia were examined by light microscopy. RESULTS: The ear deformities included deformity of the auricle, atresia of the external auditory canal, and malformation of the tympanic cavity and ossicles. Abnormalities of the stria vascularis and the semicircular canals were also demonstrated. Further inner ear deformities were not identified in this case. CONCLUSION: These histopathologic findings appear to confirm the conductive component of the congenital hearing deficit, but a sensorineural component could not be omitted. The ear alterations favor early developmental field defects. The causes of this condition are controversial. Recent results in genetic research pertaining to the MSX class genes permit better understanding of the variety, variability, and different degrees of severity of the anomalies described here.

Selective aspects of human pathology in high-tone hearing loss of the aging inner ear.

Accompanied with aging, the thresholds for high frequency sounds may elevate and result in a progressive hearing loss described as presbycusis. Based on correlations between audiometric measures of aged patients and histologic findings garnered from postmortem examinations, four types of presbycusis have been characterized: sensory-neural, neural, strial, and conductive [Schuknecht, H.F., Gacek, M.R., 1993. Ann. Otol. Rhinol. Laryngol. 102, 1--16]. Otopathologic changes to the inner ear as a direct function of age, however, remain controversial. The focus of this investigation involves the pathological impact on remaining sensory structures in patients having sensory--neural degeneration. The current study presents seven human temporal bones extracted from patients aged 53--67 years with high-tone hearing loss and with no known history of extraordinary environmental events involving head or noise trauma, acoustic overstimulation, or ototoxicity. In previously published findings of these specimens, all but one temporal bone failed to demonstrate a meaningful correlation between audiometric measurements and loss of functional hair cell populations with secondary retrograde degeneration of nerve fibers. Using the block surface method, electron microscopic micrographs demonstrate ultrastructural changes in the cuticular plate, stereocilia, pillar cells, stria vascularis, and the spiral ligament. In all pathological specimens, the greatest incidence of degeneration was seen at the cuticular plate. Conclusively, our findings present three implications in the aging human cochlea: firstly, audiometric measures that represent a high-tone hearing loss may take various forms with respect to ultrastructural patterns of degeneration and surviving structures; secondly, the incidence of lipofuscin and lysosome granules does not correlate with the degree of hearing loss and; thirdly, as shown only in guinea pigs [Anniko, M., 1988. Scanning Microsc. 2, 1035--1041], high-tone hearing loss can be associated with deformation of the cuticular plate.

Immunohistochemical and morphological studies on the human fetal cochlea: a comparative view on methods.

The preservation of morphology and antigenicity can vary uncontrollably with human fetuses since these rely heavily on immediate fixation of the temporal bone following spontaneous abortion. Once good fixation is established, there is the question of the approach taken for morphologic and immunohistochemical studies. To achieve maximal preservation for the purpose of studying normal and pathologic fetal cochleae, commonly used preparation methods for analyzing the cochlea were reviewed and compared for both immunohistochemical and morphologic studies. Cochleae obtained after spontaneous abortion ranged from the 9th gestational week to birth. Four different methods were compared for morphologic study: the block surface method; a microslicing technique; paraffin; and celloidin sectioning. For immunohistochemical study, three methods were compared: pre-embedding; paraffin; and frozen sectioning. For morphologic preservation, the block surface method gave best overall results, showing good representation of the fetal cochlea for surface preparation, light, and electron microscopy. Celloidin sectioning was also found to show good light microscopic results for both the middle and inner ear. To achieve optimal results, preservation quality, fixation procedures, and antibody all contribute to the efficacy of a methods choice.

Cerebro-oculo-facio-skeletal syndrome as a human example for accelerated cochlear nerve degeneration.

BACKGROUND: Cerebro-oculo-facio-skeletal (COFS) syndrome is a rare autosomal-recessive disorder that includes microcephaly, severe mental retardation, and multiple congenital anomalies. Otologic findings are usually limited to descriptions of the auricles. PATIENT AND METHODS: The authors report inner ear histopathologic findings of a deceased 13-year-old patient with COFS. A histologic study of the inner ear in COFS syndrome has not yet been described. This patient was documented as having a profound bilateral sensorineural hearing loss at the age of 2 years. RESULTS: Histologic evaluation revealed accelerated neural and neuronal degeneration at the cochlear and retrocochlear levels. Remaining myelinated nerve fibers, counted in the spiral lamina, had degenerated by up to 97% when compared with normal innervation densities. Afferent nerve fibers innervating inner hair cells were completely absent, whereas medial efferent fibers to outer hair cells were found. Vestibular nerve fibers were less affected. CONCLUSION: The authors report inner ear findings that differ from animal models of primary cochlear neural degeneration and that resemble the pattern of hereditary cochlear nerve degeneration reported in Friedreich's ataxia.

Dendritic cells in precancerous lesions of the larynx.

OBJECTIVES: Hyperplastic lesions of the laryngeal mucosa can eventually develop into squamous cell carcinoma The relationship between dendritic cell infiltration of head and neck cancers and prognosis is well known. Surprisingly, data regarding dendritic cell infiltration in precancerous lesions are not available today. It was the purpose of our study to extend these observations and to investigate in more detail the density and distribution of dendritic cells in pre-cancerous lesions. STUDY DESIGN: Retrospective survey by immunohistochemistry. METHODS: For this study we investigated paraffin-embedded tissue sections of 41 specimens. Histological diagnosis disclosed precancerous lesions of the larynx in 34 cases and in 7 cases, squamous cell carcinoma Immunohistochemical study was performed using antibodies against the cell surface markers S-100, HLA-DR, CD20, CD45 RO, CD45 RA, and Lag. Typical dendritic cell distributions of the immunostained specimens were photographed and measured on a quantitative basis. The medical histories of the patients were then analyzed retrospectively. RESULTS: HLA-DR+ cells could be detected in 14 of 16 cases in mild dysplastic lesions. The infiltration of the dysplastic lesions was sparse compared to cases with higher-graded dysplastic lesions. The distribution patterns of the dendritic cells in specimens with severe dysplastic lesions, but squamous cell carcinoma were extremely similar and markedly different from those in grades I and II specimens. Memory T lymphocytes (CD45 RO+) were detected more often in the group with severe dysplastic lesions (8 of 9 cases) than in the group with squamous cell carcinoma (3 of 8 cases). The inverse became evident for CD20 and CD45 RA immunolabeling. CONCLUSIONS: Few dendritic cells were found in the precancerous lesions. This may suggest that these early lesions (grades I and H) are not efficiently monitored by the immune system. Therefore they may develop into carcinomas unimpaired by cytotoxic T cells. As the degree of malignancy rises (grade III), more dendritic cells infiltrate the tumor.

Dendritic cells in selected head and neck tumors.

Specimens from 17 head and neck tumor patients were immunohistochemically stained with monoclonal antibodies against HLA-DR, CD1a, RFD1, LAG, CD3, CD4, CD8, CD45RO, CD68, and cytokeratin to identify the nature and distribution of dendritic cells (DCs), T cells, and macrophages. Small numbers of DCs were present in all but 2 specimens. They were located between the tumor cells and in the stroma, especially in areas of inflammatory cell infiltration. Variable numbers of T lymphocytes (cytotoxic and memory type) occurred in the same locations. Numerous macrophages were found in the epithelium, in the stroma, and in the vicinity of tumor cells. The presence of DCs in head and neck tumors indicates that the organism has activated the immune surveillance system and is trying to present tumor antigens. Considering the sparsity of DCs in the malignant tissues, the T cell response can be only limited.

[Immunocytochemical study of gamma-aminobutyric acid-ergic innervation in the end-organs of human vestibule].

OBJECTIVE: To investigate gamma-aminobutyric acid-ergic (GABAergic) innervation in the end-organs of human vestibule. METHODS: A modified pre-embedding immunostaining technique of immunoelectron microscopy were applied to accomplish this study with a polyclonal antibody to gamma-aminobutyric acid. RESULTS: GABA-immunoreactive products were confined to the nerve terminals, which were rich in synaptic vesicles and the non-myelinated fibers. The GABA-immunoreactive nerve fibers synapse with afferent calices surrounding the type I hair cells. CONCLUSION: This study shows that GABAergic fibers of human vestibular end-organs belong to the vestibular efferent system.

Ultrastructural localization of ChAT-like immunoreactivity in the human vestibular periphery.

Acetylcholine (ACh) has long been considered a neurotransmitter candidate in the efferent vestibular system of mammals. Recently, choline acetyltransferase (ChAT), the synthesizing enzyme for ACh, was immunocytochemically localized in all five end-organs of the rat vestibule (Kong et al. (1994) Hear. Res. 75, 192-200). However, there is little information in the literature concerning the cholinergic innervation in the vestibular periphery of man. In the present study the ultrastructural localization of the ChAT-like immunoreactivity in the human vestibular periphery was investigated in order to reveal the cholinergic innervation in the human vestibular end-organs. A modified method of pre-embedding immunoelectron microscopy was applied. It was found that the ChAT-like immunoreactivity was located in the bouton-type vesiculated nerve terminals in the vestibular neurosensory epithelia of man. These ChAT-like immunostained nerve terminals make synaptic contacts either with afferent chalices surrounding type I vestibular sensory hair cells, or with type II vestibular sensory hair cells. These results show that the ChAT-like immunoreactivity in the human vestibular periphery is confined to the efferent vestibular system. The ChAT-containing efferents innervate both type I hair cells and type II hair cells, making postsynaptic and presynaptic contacts, respectively. This study presents evidence that ACh is a neurotransmitter candidate in the efferent vestibular system of man.

Ultrastructural localization of GABA-like immunoreactivity in the human utricular macula.

In the vertebrate vestibular periphery, gamma-aminobutyric acid (GABA) has long been presumed to be a neurotransmitter candidate. However, experimental reports about the localization and function of GABA in the vestibular systems of vertebrates are contradictory. In addition, there is no information in the literature concerning the localization of GABA in the human vestibular periphery. The present study investigates the ultrastructural localization of GABA-like immunoreactivity in the human utricular macula. A modified pre-embedding immunostaining electron microscopy technique was applied using two different commercially available polyclonal antibodies to GABA. GABA-like immunoreactivity is confined to the vesiculated nerve fibers and terminals of the human vestibular neurosensory epithelia. The GABA-containing nerve terminals make asymmetrical axo-dendritic synapses with the afferent chalices surrounding the type I sensory hair cells. Type I and type II hair cells as well as afferent chalices are devoid of GABA-like immunoreactive staining. The present study demonstrates that GABA exists in the human vestibular periphery, and that GABA is a neurotransmitter candidate of the human efferent vestibular system.

Ultrastructural localization of GABA-like immunoreactivity in the vestibular periphery of the rat.

Gamma-aminobutyric acid (GABA) is presumed to be a neurotransmitter candidate in the vestibular periphery of mammals. However, experimental reports about the localization of GABA in afferents or efferents of the vestibular systems are contradictory. It is an open question whether there are species differences in the amammalian vestibular system. The present study was designed to investigate the ultrastructural localization of GABA-like immunoreactivity in the vestibular periphery of the rat. A modified preembedding immunoelectron microscopy technique was applied using a polyclonal antibody to GABA as a marker. GABA-like immunoreactivity was revealed in the vestibular periphery of the rat, confined to the vesiculated nerve fibers and terminals of the rat vestibular neurosensory epithelia. Type I hair cells and type II hair cells as well as efferent chalices are devoid of GABA-like immunoreactive staining. These findings indicate that GABA is a neurotransmitter candidate of the efferent vestibular system of the rat.

[Immunocytochemical study of cholinergic innervation in the neurosensory epithelia of human vestibule].

OBJECTIVE: To investigate the cholinergic innervation of the neurosensory epithelia of human vestibule. METHODS: A modified preembedding immunostaining technique for immunoelectronmicroscopy was applied to this study. A polyclonal antibody to choline acetyltransferase (ChAT) was used as the marker of cholinergic fibers. RESULTS: ChAT-immunoreactive products were restricted to the nerve fibers and terminals which were rich in synaptic vesicles. The ChAT-immunoreactive fibers synaps with afferent chalice as well as with type II sensory hair cells. CONCLUSION: This study demonstrates that cholinergic fibers innervate the neurosensory epithelia of human vestible. The cholinergic fibers of human vestibular sensory epithelia belong to the vestibular efferent system.

Innervation of cholinergic vestibular efferent system in vestibular periphery of rats.

The innervation of cholinergic efferent fibers in the vestibular endorgans of the rats was investigated using a modified preembedding immunostaining technique of immunoelectron microscopy. A monoclonal antibody to choline acetyltransferase (ChAT) was used as a marker of cholinergic fibers. It was found that there were four types of cholinergic innervation in the vestibular endorgans of the rat: (1) cholinergic nerve endings formed axo-dendritic synapses with afferent chalice surrounding the type I sensory hair cells; (2) cholinergic nerve endings formed axo-somatic synapses with type II hair cells; (3) cholinergic fibers synapse with afferent nerve fibers and (4) a synaptic contact developed between cholinergic nerve endings. The results demonstrated that a multiform innervation of the cholinergic efferents exists in the rats vestibular periphery.

Dendritic cells in the normal human tympanic membrane.

Dendritic cells (DCs) are antigen-presenting cells that possess an outstanding capacity to initiate primary immune responses. They reside in the tissues in an immunologically immature state. Upon antigenic challenge in vivo or short-term culture in vitro, they undergo a maturation process and turn into mature "lymphoid DCs." Langerhans cells (LCs) of the epidermis were identified as members of this DC system. They have been demonstrated in cholesteatoma matrix and in inflamed tympanic membranes, but the normal tympanic membrane was hitherto thought to be devoid of them. To clarify this question, we removed 12 normal tympanic membranes postmortem and processed them for a sheet preparation. The epidermal layers were peeled off and immunostained with the following monoclonal antibodies: HLA-DR, OKT6/CD1a, and LAG (specific for the Birbeck granules of LCs). Two tympanic membranes were also processed for routine electron microscopy. In all epidermal sheets a dense network of DCs could be demonstrated. They showed a positive immunostaining reaction with HLA-DR, but a negative one with OKT6 and LAG. Thus, they differ in their immunohistochemical properties from typical epidermal LCs. At the ultrastructural level, DCs could also be identified, but without the typical Birbeck granules. This explains the negative reaction with the LAG antibody. These findings were extended and supported by a tissue culture examination of three normal tympanic membranes. After 3 days, typical "veiled" cells (ie, mature DCs), showing positive immunostaining with HLA-DR, could be recovered from the culture medium. In an oxidative mitogenesis assay, these cells displayed strong stimulatory capacity for resting T lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Localization of chat-like immunoreactivity in the vestibular endorgans of the rat.

In vertebrates acetylcholine (ACh) has been generally considered as a neurotransmitter of the vestibular efferent system. The precise localization and innervation of the cholinergic nerve endings in the vestibular sensory periphery is still unknown. We examined choline acetyltransferase (ChAT)-like immunoreactivity in all five endorgans of the rat vestibule with light and electron microscopy using a modified pre-embedding immunostaining technique. The results were: (1) ChAT-like immunoreactivity was widespread in all five endorgans of the vestibule and confined to the vesiculated efferent nerve endings. (2) Two types of ChAT-like immunostained nerve endings can be identified according to their size and innervation pattern: a large nerve ending and a small--middle size one. (3) Vestibular endorgans differ in their ChAT-like immunoreactivity: staining is dense in the macula of the utricule and the three ampullary cristae, but less so in the macula of the saccule. (4) We found also a regional difference of the ChAT-like immunostaining in ampullary crista. ChAT-like immunostained nerve endings were predominant in the periphery close to the semilunar plane, and less in density in the central area. These findings demonstrate that ACh is a major neurotransmitter in the vestibular efferent system.

A study of neurotransmitters in human inner ear. Preservation of human temporal bone and value of organ donation for inner ear research.

Twenty-nine human temporal bones (TBs) from 3 different groups of patients were used to investigate an effective preservation method of the inner ear and to study the suitability of TBs from organ donors for human inner ear research. Inner ears were fixed by perilymphatic perfusion and immersion fixation. Choline acetyltransferase (ChAT) and gamma-aminobutyric acid (GABA) activities were detected either by an indirect immunostaining method or by the peroxidase-anti-peroxidase (PAP) technique. The results show that the cytoarchitecture of the sensory epithelia is excellently preserved in specimens fixed within 2 h after death. ChAT- and GABA-immunoreactivities were revealed in the efferent nerve endings and fibers of the cochlea. Morphological preservation of the sensory epithelia was also good in specimens fixed within 5 h after death. However, inner ear sensory epithelia of organ donors that had died from head trauma and were in the definite brain death state for at least 7 1/2 h were severely damaged and showed cellular debris due to autolysis, although they were fixed within 2 1/2 h after death. The mechanisms underlying this damage of the sensory epithelia are discussed.

[Reconstruction of the ossicular chain: Plastipore prosthesis compared with autogenous and allogenic ossicles (author's transl)]. / Die Rekonstrucktion der Schalleitungskette: Plastipore -Prothesen im Vergleich zu autologen und allogenen Ossikula.

Morphological and audiological early and late results after reconstruction of the ossicular chain with Plastipore prosthesis (TORP's and PORP's) were compared with those achieved by using autogenous or allogenic ossicles. In particular 32 tympanoplasties with TORP's were compared with 25 cases of columella and 29 PORP cases with 75 interpositions. Only Plastipore prostheses were extruded, up to now in 11.4% of cases. The final extrusion rate will be even higher since perforations of the fascia graft or the drum over the head of the prostheses as signs of imminent extrusions were noted in 9.8% of tympanoplasties at the end of the 2-year follow-up period. However, only in one third of tympanoplasties cartilage had been interposed between the head of the prosthesis and the fascia graft or drum. Audiological results, early as well as late ones, using the mean postoperative air-bone gap as criterion of success, showed no statistically significant differences between the compared groups. Only the comparison of the mean air-bone gaps in late results versus the preoperative values seemed to favour the PORP group over the interposition group. In some PORP cases, however, greater reduction of the air-bone gap was caused by postoperative deterioration of the bone conduction threshold level. In addition, hearing gains were more lasting in the interposition than in the PORP group. Because of the high extrusion rate and the fact that the audiological results were not significantly better than in the compared groups we will cease using PORP's and will employ TORP's only with careful interposition of cartilage and then only in selected cases with good tubal function.

Secretory otitis media and mastoid pneumatization.

The objective of this study is to correlate in children with chronic secretory otitis media the extent of pneumatization with morphological and functional end results after therapy. For this purpose we examined 82 children and adolescents (147 ears), who 5 to 8 years previously were treated with insertion of ventilating tubes for chronic secretory otitis media. We evaluated the morphological and functional end results with otomicroscopy, pure tone audiometry, tympanometry and stapedial reflex testing. Roentgenograms of the temporal bones in a lateral projection were taken initially in 96 ears and at time of control in 145 ears. We judged the size of the mastoid air cell system by visual estimation and classified the mastoids according to the extent of pneumatization into three groups: large, middle-sized and small (sclerotic). Twenty-five percent of the ears had sclerotic mastoids at time of control. Statistically significant correlations exist between arrested pneumatization (sclerotic mastoids), major morphological changes in the tympanic membranes and unfavorable functional results. Also the correlation between sclerotic mastoids and the number of tube insertions required in the course of the disease is statistically significant. But no correlation can be established between the physical properties of secretions and the extent of pneumatization. Arrest of pneumatization leading to a small mastoid air cell system constitutes an unfavorable prognostic factor for the final outcome of chronic secretory otitis media.

Urinary androgen- and estrogen excretion in men with pachydermia laryngis and cancer of the larynx.

Considering the larynx as a hormone dependent secondary sex characteristic has previously led to successful antiandrogentherapy of pachydermia of the vocal cords, which may constitute a precancerous state. As a first step to further evaluate the endocrine state of patients with precancerous lesions or cancer of the larynx, the urinary excretion of 17-hydroxysteroids, 17-ketosteroids, testosterone and estrogens has been determined in male patients with pachydermia laryngis (n = 15) or cancer of the larynx (n = 20) as compared to controls with different other otorhino-laryngological affections (n = 20). No difference between groups was found in 17-hydroxysteroids and no significant difference in 17-ketosteroid excretion. The pachydermia group as a whole showed significantly increased levels of testosterone (p = 0.01) and estrogen (p = 0.04) of 64.6 +/- 39.9 microgram/24 hr testosterone versus 34.7 +/- 19.3 microgram/24 hr in controls and 31.7 +/- 16 microgram/24 hr in laryngeal cancer and 277 +/- 14.8 microgram/24 hr total estrogens versus 19.1 +/- 12 microgram/24 hr and 17.8 +/- 8.1 microgram/24 hr respectively. These data further support the idea of hormonal factors playing an important role in the pathogenesis of pachydermia and thus possibly cancer of the larynx. So far, however, they do not permit definite conclusions on the pathogenetic mechanisms involved.