scholarly journals THE ULTRASTRUCTURE OF THE SENSORY HAIRS AND ASSOCIATED ORGANELLES OF THE COCHLEAR INNER HAIR CELL, WITH REFERENCE TO DIRECTIONAL SENSITIVITY

1966 ◽  
Vol 29 (3) ◽  
pp. 497-505 ◽  
Author(s):  
Arndt J. Duvall ◽  
Åke Flock ◽  
Jan Wersäll
Keyword(s):  
Guinea Pig ◽  
Hair Cell ◽  
Basal Body ◽  
Organ Of Corti ◽  
Sensory Cells ◽  
Directional Sensitivity ◽  
Inner Hair Cell ◽  
Lateral Line Organ ◽  
Sensory Hairs ◽  
Line Organ

From the apical end of the inner hair cell of the organ of Corti in the guinea pig cochlea protrude four to five rows of stereocilia shaped in a pattern not unlike the wings of a bird. In the area devoid of cuticular substance facing toward the tunnel of Corti lies a consistently present centriole. The ultrastructure of this centriole is similar to that of the basal body of the kinocilium located in the periphery of the sensory hair bundles in the vestibular and lateral line organ sensory cells and to that of the centrioles of other cells. The physiological implications of the anatomical orientation of this centriole are discussed in terms of directional sensitivity.

scholarly journals THE ULTRASTRUCTURE OF THE KINOCILIUM OF THE SENSORY CELLS IN THE INNER EAR AND LATERAL LINE ORGANS

1965 ◽  
Vol 25 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Åke Flock ◽  
Arndt J. Duvall
Keyword(s):  
Inner Ear ◽  
Lateral Line ◽  
Basal Body ◽  
Teleost Fish ◽  
Receptor Cell ◽  
Sensory Cells ◽  
Directional Sensitivity ◽  
Sensory Hairs ◽  
Basal Foot

The bundle of sensory hairs protruding from the top of each receptor cell in the vestibular and lateral line organs in the teleost fish (burbot) Lota vulgaris is composed of a number of stereocilia and one kinocilium located in the periphery of the bundle. The ultrastructure of the kinocilium and its basal body is described. It is found that the kinocilium is morphologically polarized by the asymmetric arrangement of its component fibers and of the basal body by the presence of a basal foot. Peripheral fibers 5 and 6 of the kinocilium and the basal foot of the basal body are oriented away from the stereocilia; that is, in a direction coinciding with the direction of excitatory stimulation. The findings are discussed in terms of directional sensitivity.

Morphology of Inner Hair Cell Stereocilia in C57BL/6J Mice as Studied by Scanning Electron Microscopy

1983 ◽  
Vol 91 (4) ◽  
pp. 421-426 ◽  
Author(s):  
Terry J. Garfinkle ◽  
James C. Saunders
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Hair Cell ◽  
Mammalian Species ◽  
Total Surface Area ◽  
Nerve Fibers ◽  
Inner Hair Cell ◽  
Tuning Curves ◽  
Sensory Hairs ◽  
Scanning Electron

The observation that hair cell tuning curves exhibit frequency selectivity as sharply tuned as that seen in auditory nerve fibers has prompted closer examination of the sensory hairs or stereocilia. The present study was designed to examine the morphologic organization of inner hair cell stereocilia in a mammalian species, the neonatal C57BL/6J mouse. The cochleae of mice were fixed in OSO4, dehydrated, dissected, and prepared for scanning electron microscopy. An examination of the number of stereocilia per inner hair cell revealed an orderly decrease from base to apex. Conversely, there was a 300% increase in the height of the tallest stereocilia, a 100% increase in the height of the middle row stereocilia, and a 30% increase in shortest stereocilia from base to apex. The total surface area of the stereocilia, per hair cell, was shown to increase by approximately 250% from the base to the apex of the cochlea.

Electroreceptors and Direction Specific Arrangement in the Lateral Line System of Salamanders?

1981 ◽  
Vol 36 (5-6) ◽  
pp. 493-496 ◽  
Author(s):  
Bernd Fritzsch
Keyword(s):  
Lateral Line ◽  
Fiber Bundles ◽  
Sensory Cells ◽  
Lateral Line System ◽  
Line System ◽  
Lateral Line Organ ◽  
Posterior Lateral Line ◽  
Afferent Fibers ◽  
Lateral Line Afferents ◽  
Line Organ

Abstract The arrangement of the lateral line afferents of salamanders as revealed by transganglionic staining with horse­ radish peroxidase is described. Each lateral line organ is supplied by two fibers only. In the medulla these two afferent fibers run in separate fiber bundles. It is suggested, that only those fibers contacting lateral line sensory cells with the same polarity form together one bundle. Bundles formed by anterior or posterior lateral line afferents are also clearly separated. Beside the lateral line organs smaller pit organs are described. These organs are supplied by one afferent only which reveals an arrangement in the medulla different from that of the lateral line afferents. Based on anatomical facts, these small pit organs are considered to be electroreceptors. Centrifugally projecting neurons, most probably efferents, are described in the medulla.

An evaluation of the use of scanning and transmission electronmicroscopy in a study of the gentamicin-damaged guinea-pig organ of Corti

1979 ◽  
Vol 93 (1) ◽  
pp. 7-23 ◽  
Author(s):  
E. S. Harpur ◽  
J. B. Bridges
Keyword(s):  
Guinea Pig ◽  
Organ Of Corti ◽  
Cell Loss ◽  
Sensory Cells ◽  
Pathological Changes ◽  
Transmission Electron ◽  
Scanning Electronmicroscopy ◽  
Suitable Technique ◽  
Transmission Electronmicroscopy ◽  
Surface Changes

AbstractScanning electronmicroscopy and transmission electronmicroscopy were used to study the normal and gentamicin-damaged guinea-pig organ of Corti. Scanning electronmicroscopy was principally used to locate the lesion and quantify the cell loss but also permitted a detailed study to be made of the degenerative surface changes. However, since consistent surface changes are not seen until intracellular degeneration has progressed to a great extent, scanning electronmicroscopy is not a suitable technique for identifying early degenerative changes in the sensory cells of the organ of Corti. Consequently, before conclusions may be drawn about the absence of pathological changes in the neuro-epithelium it also should be examined using transmission electron-microscopy.

scholarly journals Hearing impairment due to Mir183/96/182 mutations suggests both loss and gain of function effects

2020 ◽  
pp. dmm.047225
Author(s):  
Morag A. Lewis ◽  
Francesca Di Domenico ◽  
Neil J. Ingham ◽  
Haydn M. Prosser ◽  
Karen P. Steel
Keyword(s):  
Hearing Loss ◽  
Hair Cell ◽  
Target Genes ◽  
Normal Hearing ◽  
Null Alleles ◽  
Sensory Cells ◽  
Seed Region ◽  
Inner Hair Cell ◽  
Progressive Hearing Loss ◽  
Altered Expression

The microRNA miR-96 is important for hearing, as point mutations in humans and mice result in dominant progressive hearing loss. Mir96 is expressed in sensory cells along with Mir182 and Mir183, but the roles of these closely-linked microRNAs are as yet unknown. Here we analyse mice carrying null alleles of Mir182, and of Mir183 and Mir96 together to investigate their roles in hearing. We found that Mir183/96 heterozygous mice had normal hearing and homozygotes were completely deaf with abnormal hair cell stereocilia bundles and reduced numbers of inner hair cell synapses at four weeks old. Mir182 knockout mice developed normal hearing then exhibited progressive hearing loss. Our transcriptional analyses revealed significant changes in a range of other genes, but surprisingly there were fewer genes with altered expression in the organ of Corti of Mir183/96 null mice compared with our previous findings in Mir96Dmdo mutants, which have a point mutation in the miR-96 seed region. This suggests the more severe phenotype of Mir96Dmdo mutants compared with Mir183/96 mutants, including progressive hearing loss in Mir96Dmdo heterozygotes, is likely to be mediated by the gain of novel target genes in addition to the loss of its normal targets. We propose three mechanisms of action of mutant miRNAs; loss of targets that are normally completely repressed, loss of targets whose transcription is normally buffered by the miRNA, and gain of novel targets. Any of these mechanisms could lead to a partial loss of a robust cellular identity and consequent dysfunction.

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