Vibration of beads placed on the basilar membrane in the basal turn of the cochlea

1999 ◽  
Vol 106 (6) ◽  
pp. L59-L64 ◽  
Author(s):  
Nigel P. Cooper
Keyword(s):  
Basilar Membrane ◽  
Basal Turn

Electron Microscopic Findings in Presbycusic Degeneration of the Basal Turn of the Human Cochlea

1979 ◽  
Vol 87 (6) ◽  
pp. 818-836 ◽  
Author(s):  
Joseph B. Nadol
Keyword(s):  
Light Microscopy ◽  
Hair Cells ◽  
Basilar Membrane ◽  
Ganglion Cells ◽  
Nerve Fibers ◽  
Degenerative Changes ◽  
Supporting Cells ◽  
Neural Degeneration ◽  
Basal Turn ◽  
Temporal Bones

Three human temporal bones with presbycusis affecting the basal turn of the cochlea were studied by light and electron microscopy. Conditions in two ears examined by light microscopy were typical of primary neural degeneration, with a descending audiometric pattern, loss of cochlear neurons in the basal turn, and preservation of the organ of Corti. Ultrastructural analysis revealed normal hair cells and marked degenerative changes of the remaining neural fibers, especially in the basal turn. These changes included a decrease in the number of synapses at the base of hair cells, accumulation of cellular debris in the spiral bundles, abnormalities of the dendritic fibers and their sheaths in the osseous spiral lamina, and degenerative changes in the spiral ganglion cells and axons. These changes were interpreted as an intermediate stage of degeneration prior to total loss of nerve fibers and ganglion cells as visualized by light microscopy. In the third ear the changes observed were typical of primary degeneration of hair and supporting cells in the basal turn with secondary neural degeneration. Additional observations at an ultrastructural level included maintenance of the tight junctions of the scala media despite loss of both hair and supporting cells, suggesting a capacity for cellular “healing” in the inner ear. Degenerative changes were found in the remaining neural fibers in the osseous spiral lamina. In addition, there was marked thickening of the basilar membrane in the basal turn, which consisted of an increased number of fibrils and an accumulation of amorphous osmiophilic material in the basilar membrane. This finding supports the concept that mechanical alterations may occur in presbycusis of the basal turn.

Comparison of Cochlear Histopathology following Two Implant Designs for Use in Scala Tympani

1980 ◽  
Vol 89 (2_suppl) ◽  
pp. 11-14 ◽  
Author(s):  
Dwight Sutton ◽  
Josef M. Miller ◽  
Bryan E. Pfingst
Keyword(s):  
Basilar Membrane ◽  
Ganglion Cells ◽  
Stria Vascularis ◽  
Spiral Ganglion ◽  
Mechanical Damage ◽  
Scala Tympani ◽  
Basal Turn ◽  
Induced Changes

Two designs of intracochlear implants were evaluated for their histopathologic effects in the monkey ear. A molded electrode designed to fit the contour of the basal turn of the scala tympani tended to create basilar membrane fistulas and osseous spiral lamina fracture, along with relatively extensive loss of spiral ganglion cells in sites adjacent to the implant. A delicate, free-fit electrode induced local encapsulation but little or no mechanical damage and limited degeneration of spiral ganglion cells. Both electrode types occasionally induced changes in stria vascularis.

Comparative Measurements of Cochlear Apparatus

1968 ◽  
Vol 11 (2) ◽  
pp. 229-235 ◽  
Author(s):  
Makoto Igarashi ◽  
Robert G. Mahon ◽  
Shizuo Konishi
Keyword(s):  
Cross Section ◽  
Basilar Membrane ◽  
Stria Vascularis ◽  
The Other ◽  
Tectorial Membrane ◽  
Spiral Ligament ◽  
Scala Tympani ◽  
Basal Turn ◽  
Temporal Bones ◽  
Scala Vestibuli

Micromeasurements of horizontal midmodiolar sections of temporal bones were performed to obtain the dimensions of the different cochlear partitions in the squirrel monkey, the cat, and the rat. The width of the basilar membrane and the tectorial membrane were larger in the apical turn than in the basal turn in all three species. The thickness of the spiral ligament, the width of Reissner’s membrane, and the width of the stria vascularis were larger in the basal turn than in the apical turn. The cross-section areas of scala vestibuli and scala tympani in the three species were larger in the basal turn than in the other turns.

Basilar membrane vibration in the basal turn of the sensitive gerbil cochlea

2001 ◽  
Vol 151 (1-2) ◽  
pp. 48-60 ◽  
Author(s):  
Tianying Ren ◽  
Alfred L Nuttall
Keyword(s):  
Basilar Membrane ◽  
Basal Turn ◽  
Membrane Vibration

A technique for protecting delicate specimens during processing

1989 ◽  
Vol 47 ◽  
pp. 982-983
Author(s):  
R.J. Mount ◽  
R.V. Harrison
Keyword(s):  
Basilar Membrane ◽  
Low Cost ◽  
Organ Of Corti ◽  
Region Of Interest ◽  
Sensory Epithelium ◽  
Physical Damage ◽  
Air Drying ◽  
Specimen Handling ◽  
Two Component

The sensory end organ of the ear, the organ of Corti, rests on a thin basilar membrane which lies between the bone of the central modiolus and the bony wall of the cochlea. In vivo, the organ of Corti is protected by the bony wall which totally surrounds it. In order to examine the sensory epithelium by scanning electron microscopy it is necessary to dissect away the protective bone and expose the region of interest (Fig. 1). This leaves the fragile organ of Corti susceptible to physical damage during subsequent handling. In our laboratory cochlear specimens, after dissection, are routinely prepared by the O-T- O-T-O technique, critical point dried and then lightly sputter coated with gold. This processing involves considerable specimen handling including several hours on a rotator during which the organ of Corti is at risk of being physically damaged. The following procedure uses low cost, readily available materials to hold the specimen during processing ,preventing physical damage while allowing an unhindered exchange of fluids.Following fixation, the cochlea is dehydrated to 70% ethanol then dissected under ethanol to prevent air drying. The holder is prepared by punching a hole in the flexible snap cap of a Wheaton vial with a paper hole punch. A small amount of two component epoxy putty is well mixed then pushed through the hole in the cap. The putty on the inner cap is formed into a “cup” to hold the specimen (Fig. 2), the putty on the outside is smoothed into a “button” to give good attachment even when the cap is flexed during handling (Fig. 3). The cap is submerged in the 70% ethanol, the bone at the base of the cochlea is seated into the cup and the sides of the cup squeezed with forceps to grip it (Fig.4). Several types of epoxy putty have been tried, most are either soluble in ethanol to some degree or do not set in ethanol. The only putty we find successful is “DUROtm MASTERMENDtm Epoxy Extra Strength Ribbon” (Loctite Corp., Cleveland, Ohio), this is a blue and yellow ribbon which is kneaded to form a green putty, it is available at many hardware stores.

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