The cochlea contains macrophages. These cells participate in inflammatory responses to cochlear pathogenesis. However, it is not clear how and when these cells populate the cochlea during postnatal development. The current study aims to determine the postnatal development of cochlear macrophages with the focus on macrophage development in the organ of Corti and the basilar membrane. Cochleae were collected from C57BL/6J mice at ages of postnatal day (P) 1 to P21, as well as from mature mice (1-4 months). Macrophages were identified based on their expression of F4/80 and Iba1, as well as their unique morphologies. Two sets of macrophages were identified in the regions of the organ of Corti and the basilar membrane. One set resides on the scala tympani side of the basilar membrane. These cells have a round shape at P1 and start to undergo site-specific differentiation at P4. Apical macrophages adopt a dendritic shape. Middle and basal macrophages take on an irregular shape with short projections. Basal macrophages further differentiate into an amoeboid shape. The other set of macrophages resides above the basilar membrane, either beneath the cells of the organ of Corti or along the spiral vessel of the basilar membrane. As the sensory epithelium matures, these cells undergo developmental death with the phenotypes of apoptosis. Macrophages are also identified in the spiral ligament, spiral limbus, and neural regions. Their numbers decrease during postnatal development. Together, these results suggest a dynamic rearrangement of the macrophage population during postnatal cochlear development.
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http://dx.doi.org/10.1016/j.heares.2018.05.010 | DOI Listing |
Int J Mol Sci
December 2024
Caruso Department of Otolaryngology-Head and Neck Surgery, University of Southern California, Los Angeles, CA 90033, USA.
Novel therapeutic delivery systems and delivery methods to the inner ear are necessary to treat hearing loss and inner ear disorders. However, numerous barriers exist to therapeutic delivery into the bone-encased and immune-privileged environment of the inner ear and cochlea, which makes treating inner ear disorders challenging. Nanoparticles (NPs) are a type of therapeutic delivery system that can be engineered for multiple purposes, and posterior semicircular canal (PSCC) infusion is a method to directly deposit them into the cochlea.
View Article and Find Full Text PDFJ Biomech Eng
January 2025
School of Aerospace and Mechanical Engineering, University of Oklahoma, 865 Asp Ave, Norman, OK 73019, USA.
Hearing loss is highly related to acoustic injuries and mechanical damage of ear tissues. The mechanical responses of ear tissues are difficult to measure experimentally, especially cochlear hair cells within the organ of Corti (OC) at microscale. Finite element (FE) modeling has become an important tool for simulating acoustic wave transmission and studying cochlear mechanics.
View Article and Find Full Text PDFJ Otol
October 2024
The Institute of Audiology and Balance Science, Xuzhou Medical University, Xuzhou, Jiangsu, 221004, China.
Objective: This study aims to explore the expression patterns of cysteine string protein alpha (CSPα) and cysteine string protein beta (CSPβ) in the mammalian inner ear, with an emphasis on their temporal dynamics during the developmental stages of C57BL/6 mice.
Methods: We utilized immunofluorescence staining to assess the localization and distribution of CSPα and CSPβ within the inner ears of C57BL/6 mice and miniature pigs. Additionally, this method facilitated the investigation of their temporal expression profiles.
Front Neurol
December 2024
Department of Otorhinolaryngology-Head and Neck Surgery, Tongji Medical College, Union Hospital, Huazhong University of Science and Technology, Wuhan, China.
Background: The pathological hallmark of Ménière's disease is endolymphatic hydrops, which can lead to an increase in basilar membrane stiffness and, consequently, an acceleration of the traveling wave of sound. The cochlear hydrops analysis masking procedure (CHAMP), which is an auditory brainstem response test masked at various frequencies with high-pass noise masking, uses the principle of the traveling wave velocity theory to determine the presence of endolymphatic hydrops.
Purpose: This study aimed to review the previous results of the CHAMP, expound the principles and key indicators, and discuss its clinical significance in diagnosing Ménière's disease.
Mol Neurobiol
December 2024
Senior Department of Otolaryngology-Head & Neck Surgery, the Sixth Medical Center of PLA General Hospital, Beijing, 100853, China.
Noise exposure is one of the most common causes of sensorineural hearing loss. Although many studies considered inflammation to be a major contributor to noise-induced hearing loss, the process of cochlear inflammation is still unclear. Studies have found that activation of the NF-κB signaling pathway results in the accumulation of macrophages in the inner ear plays an important role in hair cell damage.
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