Salvatore Iurato

Intercellular junctions and other membrane specializations in developing spinal ganglia: a freeze-fracture study.

Intercellular junctions and other membrane specializations of neuroblasts and satellite cells were studied in spinal ganglia of chick embryos at the 4th, 10th, and 16th incubation days using the freeze-fracture technique. At the 4th day neuroblasts are closely arranged and connected by gap junctions. At the 10th day, instead, satellite cells appear interposed between neuroblasts so the gap junctions previously joining the latter are no longer evident. These temporary junctions probably play a role in cell differentiation and intercellular adhesion. Together with adhering junctions, gap junctions might maintain the cell organization of the ganglionic rudiment, which at the 4th day still lacks connective tissue. At the 10th day adjacent satellite cells display on their split plasma membrane small gap junctions, short, usually isolated strands recalling those composing zonulae occludentes, and orthogonal particle assemblies. These two latter specializations are still evident at the 16th day. The possible significance of these specializations is briefly discussed.

Fracture faces of the junctional complexes in the reticular membrane of the organ of corti

The junctional complexes in the reticular membrane of the organ of Corti have been investigated in chinchilla inner ear by the freeze-fracture method. Extremely developed zonulae occludentes were observed where the supporting cells contact each other and the sensory cells. These junctions can be considered “very tight” and completely seal off the tunnel of Corti, Nuels space and the outer tunnel from the endolymph, as observed by investigations carried out by using tracers. The zonulae occludentes between Hensens cells are always uninterrupted but considerably lower than among supporting and sensory cells.

Hearing results of ossiculoplasty in Austin-Kartush group A patients.

Objective To compare hearing results in patients who underwent ossiculoplasty for Austin-Kartush group A impairments (incus erosion, malleus handle present, stapes superstructure present) with the results in patients with an intact ossicular chain who required only myringoplasty. The literature on hearing results of ossiculoplasty with different types of prostheses and different techniques is reviewed. Patients and Study Design This study retrospectively reviews a series of 181 consecutive ossiculoplasties and 204 consecutive myringoplasties. Setting The study was carried out partly at a private practice and partly in an academic tertiary referral center. Main Outcome Measures This study complies with levels 1 and 2 of the guidelines recommended by the American Academy of Otolaryngology - Head and Neck Surgery (1995). Results When success was defined as a postoperative air-bone gap within 10 dB, the success rate was higher for myringoplasty (81%) than for ossiculoplasty (55%). When success was defined as a postoperative air-bone gap within 20 dB, the success rate was 97% in myringoplasties and 85% in ossiculoplasties. There was no significant deterioration over time of the mean postoperative air-bone gap for any frequency. Conclusion Cumulative data from several authors show that ∼50% of patients undergoing partial ossiculoplasty have a postoperative air-bone gap of 0 to 10 dB, and 80% have a postoperative air-bone gap of 0 to 20 dB. Equally good results may be achieved with autograft (no difference was found between interposition of the incus or the head of the malleus), homograft, or alloplastic partial prostheses. With alloplastic total prostheses, 36% of patients have a postoperative air-bone gap of 0 to 10 dB, and 74% have a postoperative air-bone gap of 0 to 20 dB.

Brain herniation into the middle ear: two idiopathic cases treated by a combined intracranial-mastoid approach

One hundred thirty‐nine cases of brain herniation into the middle ear and mastoid have been reported in the world literature during the last 40 years. In 29 cases the herniation was idiopathic. In idiopathic cases, intermittent CSF otorhinorrhea, a history of intermittent “serous otitis media,” and a conductive hearing loss were the main clinical findings. Polytomography or CT‐scan revealed a tegmen antri or tympani defect in some patients. There are three surgical approaches for treatment of brain herniation into the middle ear: neurosurgical, otological, and combined.

Functional histopathology of the human audio-vestibular organ. Euro-Data-Hearing.

The present paper describes the setting-up of a new project, sponsored by the Commission of the European Communities, to promote the study of functional histopathology of the human audio-vestibular organ. The project has the purpose of co-ordinating in Europe morphological research on the hearing and equilibrium organ and promoting the comparison of data from clinical, physiological and morphological studies in the field of hearing and equilibrium impairment. A manual (Iurato et al., 1982) has been prepared with the objectives of (1) stimulating clinicians to participate in the project, (2) encouraging the collection of audiological data for comparison with pathology, and (3) supplying clinicians with the necessary information about the technique of fixation and preparation of the specimens. The fixation procedures for the two major techniques of studying ear pathology: (1) microdissection and electron microscopy, and (2) embedding of the whole block for serial sectioning and light microscopy, are described in detail. Special paragraphs deal with the technique of fixation of the brain and with the technique of removal of the temporal bones and brain at autopsy. The instructions for delivery of the specimens and the publication rules are enclosed in the main body of the manual. Appendix 1 contains a list of the participating laboratories. Appendix 2 deals with autopsy legislation in the different European countries. Appendix 3 contains the senders data sheet which supplies the instructions for collecting the clinical history of the patient and the audiological and vestibular data.

The junctions of the spindle-shaped cells of the stria vascularis: A link that completes the barrier between perilymph and endolymph

It is current opinion that the intercellular spaces of the stria vascularis represent a closed compartment isolated from the endolymph by the tight junctions of the marginal cells and from the perilymph by the junctional complexes of the basel cells. However, it has not yet been investigated whether these two barriers meet at the stria margins toward Reissners membrane and the spiral prominence. Possible candidates for this sealing could be junctions between the spindle-shaped cells. In the present study freeze-fracture replicas of guinea pig specimens fixed in the presence of filipin were used in order to investigate the junctions of the spindle-shaped cells and to localize the cholesterol in their plasma membrane. Replicas reveal that, below the belt-like apical zonula occludens, the basolateral plasma membranes of the spindle-shaped cells adjacent to each other and to the basal cells are joined over their entire extension by a large number of junctional strands intermingled with numerous filipin-cholesterol-complexes. Gap junctions are present in the meshes formed by these junctional strands. Thus, the plasma membrane of the spindle-shaped cells shows morphological and cytochemical characteristics which indicate that they are the anatomical components completing the barrier isolating the intrastrial compartment from the surrounding fluids.

Multicentre evaluation of the temporal bones obtained from a patient with suspected Menière's disease.

A multicentre study of the inner ears of an 88-year-old patient with vertiginous spells and severe hearing loss in the left ear was performed, employing regular and block surface preparations, light and electron microscopy with qualitative and quantitative evaluation of the cochlear and vestibular nerves. There was severe hydrops of the left cochlea and saccule. Reissners membrane extended into the vestibule and herniated into the perilymphatic space of the non-ampullated end of the horizontal canal. Furthermore, the short canal connecting the posterior ampulla with the utricle had a small, exceedingly thin balloon-like expansion. Only slight hydrops limited to the cochlea was found in the right ear. Sensorineural degeneration was much more pronounced in the left cochlea than in the right. The number of cochlear and vestibular nerve fibres was greatly reduced in the left ear where more fibres with degenerative changes were present. In both specimens the number of myelinated nerve fibres in osseous spiral lamina was smaller than that in the cochlear nerve in the internal auditory canal. Changes occurred in the endolymphatic sacs but were considered non-specific. In this case severe, apparently progressive hydrops and sensorineural degeneration, characteristic of Menières disease, were associated with atypical onset of clinical symptoms at a late age.

Cholesteatoma in Children: Histopathologic Findings in Middle Ear Ossicles

Middle ear ossicles removed during ear surgery in 40 patients were examined in order to compare the histopathologic changes in children with those observed in adults. Bone resorption, mainly localized at the level of the periosteum and haversian canals in adults, was much more extensive in children. Replacement of bone by fibrous granulation tissue was observed in 60% of childrens ossicles and in 27% of those belonging to adults. In children, extensive active resorptive osteitis of the ossicles was frequently associated with intensive round cell infiltration, which seems to play an important role in bone absorption and in the aggressiveness of cholesteatoma.

Microdissection, Cytocochleogram and Transmission Electron Microscopy: a Technique for a Comprehensive Evaluation of Human Cochlear Pathology

A technique combining microdissection with cytocochleogram and TEM is described as a tool for studying human cochlear pathology. It is recommended in cases well studied from a clinical point of view and with a short time interval between death and fixation.

Metaplasic Bone Tissue in Tympanosclerosis

Two different tissues have been observed in specimens of tympanosclerotic material studied under light and electron microscopy. The first, devoid of cells and blood vessels, is a dense fibrous tissue similar to that already described in fibrous tympanosclerosis. The second resembles a bone tissue, containing osteocytes and vascular channels; it is laid down by metaplasic fibroblasts following the invasion of the first tissue by osteoclasts and blood vessels after its calcification.