Stria Vascularis
A layer of stratified EPITHELIUM forming the endolymphatic border of the cochlear duct at the lateral wall of the cochlea. Stria vascularis contains primarily three cell types (marginal, intermediate, and basal), and capillaries. The marginal cells directly facing the ENDOLYMPH are important in producing ion gradients and endochoclear potential.
Endolymph
Cochlea
Cochlear Duct
A spiral tube that is firmly suspended in the bony shell-shaped part of the cochlea. This ENDOLYMPH-filled cochlear duct begins at the vestibule and makes 2.5 turns around a core of spongy bone (the modiolus) thus dividing the PERILYMPH-filled spiral canal into two channels, the SCALA VESTIBULI and the SCALA TYMPANI.
Ear, Inner
The essential part of the hearing organ consists of two labyrinthine compartments: the bony labyrinthine and the membranous labyrinth. The bony labyrinth is a complex of three interconnecting cavities or spaces (COCHLEA; VESTIBULAR LABYRINTH; and SEMICIRCULAR CANALS) in the TEMPORAL BONE. Within the bony labyrinth lies the membranous labyrinth which is a complex of sacs and tubules (COCHLEAR DUCT; SACCULE AND UTRICLE; and SEMICIRCULAR DUCTS) forming a continuous space enclosed by EPITHELIUM and connective tissue. These spaces are filled with LABYRINTHINE FLUIDS of various compositions.
Cochlear Microphonic Potentials
Hyperpigmentation
Excessive pigmentation of the skin, usually as a result of increased epidermal or dermal melanin pigmentation, hypermelanosis. Hyperpigmentation can be localized or generalized. The condition may arise from exposure to light, chemicals or other substances, or from a primary metabolic imbalance.
Spiral Ligament of Cochlea
A spiral thickening of the fibrous lining of the cochlear wall. Spiral ligament secures the membranous COCHLEAR DUCT to the bony spiral canal of the COCHLEA. Its spiral ligament fibrocytes function in conjunction with the STRIA VASCULARIS to mediate cochlear ion homeostasis.
Spiral Ganglion
The sensory ganglion of the COCHLEAR NERVE. The cells of the spiral ganglion send fibers peripherally to the cochlear hair cells and centrally to the COCHLEAR NUCLEI of the BRAIN STEM.
Hearing Loss
Organ of Corti
The spiral EPITHELIUM containing sensory AUDITORY HAIR CELLS and supporting cells in the cochlea. Organ of Corti, situated on the BASILAR MEMBRANE and overlaid by a gelatinous TECTORIAL MEMBRANE, converts sound-induced mechanical waves to neural impulses to the brain.
Hair Cells, Auditory
Sensory cells in the organ of Corti, characterized by their apical stereocilia (hair-like projections). The inner and outer hair cells, as defined by their proximity to the core of spongy bone (the modiolus), change morphologically along the COCHLEA. Towards the cochlear apex, the length of hair cell bodies and their apical STEREOCILIA increase, allowing differential responses to various frequencies of sound.
Temporal Bone
Either of a pair of compound bones forming the lateral (left and right) surfaces and base of the skull which contains the organs of hearing. It is a large bone formed by the fusion of parts: the squamous (the flattened anterior-superior part), the tympanic (the curved anterior-inferior part), the mastoid (the irregular posterior portion), and the petrous (the part at the base of the skull).
Goiter
Enlargement of the THYROID GLAND that may increase from about 20 grams to hundreds of grams in human adults. Goiter is observed in individuals with normal thyroid function (euthyroidism), thyroid deficiency (HYPOTHYROIDISM), or hormone overproduction (HYPERTHYROIDISM). Goiter may be congenital or acquired, sporadic or endemic (GOITER, ENDEMIC).
Anion Transport Proteins
Presbycusis
Gradual bilateral hearing loss associated with aging that is due to progressive degeneration of cochlear structures and central auditory pathways. Hearing loss usually begins with the high frequencies then progresses to sounds of middle and low frequencies.
Round Window, Ear
Septal Nuclei
Neural nuclei situated in the septal region. They have afferent and cholinergic efferent connections with a variety of FOREBRAIN and BRAIN STEM areas including the HIPPOCAMPAL FORMATION, the LATERAL HYPOTHALAMUS, the tegmentum, and the AMYGDALA. Included are the dorsal, lateral, medial, and triangular septal nuclei, septofimbrial nucleus, nucleus of diagonal band, nucleus of anterior commissure, and the nucleus of stria terminalis.
Vestibule, Labyrinth
An oval, bony chamber of the inner ear, part of the bony labyrinth. It is continuous with bony COCHLEA anteriorly, and SEMICIRCULAR CANALS posteriorly. The vestibule contains two communicating sacs (utricle and saccule) of the balancing apparatus. The oval window on its lateral wall is occupied by the base of the STAPES of the MIDDLE EAR.
Evoked Potentials, Auditory, Brain Stem
Kanamycin
Antibiotic complex produced by Streptomyces kanamyceticus from Japanese soil. Comprises 3 components: kanamycin A, the major component, and kanamycins B and C, the minor components.
Hearing Disorders
Hair Cells, Auditory, Outer
Sensory cells of organ of Corti. In mammals, they are usually arranged in three or four rows, and away from the core of spongy bone (the modiolus), lateral to the INNER AUDITORY HAIR CELLS and other supporting structures. Their cell bodies and STEREOCILIA increase in length from the cochlear base toward the apex and laterally across the rows, allowing differential responses to various frequencies of sound.
Hearing Loss, Sensorineural
Hearing loss resulting from damage to the COCHLEA and the sensorineural elements which lie internally beyond the oval and round windows. These elements include the AUDITORY NERVE and its connections in the BRAINSTEM.
Hearing Loss, Noise-Induced
Hearing loss due to exposure to explosive loud noise or chronic exposure to sound level greater than 85 dB. The hearing loss is often in the frequency range 4000-6000 hertz.
Guinea Pigs
Evoked Potentials, Auditory
Freeze Fracturing
Preparation for electron microscopy of minute replicas of exposed surfaces of the cell which have been ruptured in the frozen state. The specimen is frozen, then cleaved under high vacuum at the same temperature. The exposed surface is shadowed with carbon and platinum and coated with carbon to obtain a carbon replica.