Related Experiment Video
Updated: Dec 26, 2025
07:40
Dissection of the Auditory Bulla in Postnatal Mice: Isolation of the Middle Ear Bones and Histological Analysis
Published on: January 4, 2017
31.5K
Nanostructure of mouse otoconia.
Dimitra Athanasiadou1, Wenge Jiang1, Natalie Reznikov2
1Faculty of Dentistry, McGill University, Montreal, QC H3A 0C7, Canada.
Journal of Structural Biology
|March 7, 2020
Summary
Mammalian otoconia, crucial for balance, possess a calcite nanostructure. The protein osteopontin (OPN) is found on the otoconia surface, influencing its nanostructure and potentially contributing to internal structure formation.
Area of Science:
- Biomineralization
- Crystallography
- Cell Biology
Background:
- Mammalian otoconia are calcium carbonate structures in the inner ear essential for balance and linear acceleration detection.
- The mineral phase of otoconia is calcite, exhibiting single-crystal-like X-ray diffraction properties.
- Osteopontin (OPN) is a mineral-binding protein found in otoconia, known to influence mineralization in various biological tissues.
Purpose of the Study:
- To elucidate the mineral nanostructure of mammalian otoconia.
- To determine the distribution of osteopontin (OPN) within mouse otoconia.
- To investigate the role of OPN in otoconia mineralization and nanostructure formation.
Main Methods:
- Scanning electron microscopy (SEM) and atomic force microscopy (AFM) for surface and internal nanostructure analysis.
- Transmission electron microscopy (TEM) and electron tomography for high-resolution nanostructure and nanograin imaging.
- X-ray diffraction (XRD), Raman spectroscopy, and X-ray absorption spectroscopy (XAS) for mineral phase and crystallinity assessment.
- Colloidal-gold immunolabeling for OPN localization and in vitro calcite growth experiments.
Main Results:
- Mouse otoconia exhibit an internal nanostructure of approximately 50 nm, with nanograins as small as 10 nm.
- XRD analysis confirmed crystallite sizes in the range of 73 nm and smaller in mature otoconia.
- No amorphous calcium carbonate was detected in mature otoconia using Raman and XAS.
- OPN was localized to the otoconia surface, correlating with observed surface nanostructure.
- In vitro experiments showed OPN addition to growing calcite produced similar surface nanostructures.
Conclusions:
- Mammalian otoconia possess a complex internal and surface nanostructure composed of calcite.
- Osteopontin (OPN) is primarily located on the otoconia surface and influences its nanostructure.
- While OPN may play a role in surface properties, other proteins likely contribute to the formation of the internal otoconia nanostructure.
Related Concept Videos
01:11The Auditory Ossicles
2.8K
The auditory ossicles of the middle ear transmit sounds from the air as vibrations to the fluid-filled cochlea. The auditory ossicles consist of two malleus (hammer) bones, two incus (anvil) bones, and two stapes (stirrups), one on each side. These bones develop during the fetal stage and are the ones to ossify first. They are fully mature at birth and do not grow afterward.
The aptly named stapes look very much like a stirrup. The three ossicles are unique to mammals, and each plays a role in...
The aptly named stapes look very much like a stirrup. The three ossicles are unique to mammals, and each plays a role in...
2.8K
01:22Hair Cells
44.0K
Hair cells are the sensory receptors of the auditory system—they transduce mechanical sound waves into electrical energy that the nervous system can understand. Hair cells are located in the organ of Corti within the cochlea of the inner ear, between the basilar and tectorial membranes. The actual sensory receptors are called inner hair cells. The outer hair cells serve other functions, such as sound amplification in the cochlea, and are not discussed in detail here.
44.0K
01:13The Cochlea
49.9K
The cochlea is a coiled structure in the inner ear that contains hair cells—the sensory receptors of the auditory system. Sound waves are transmitted to the cochlea by small bones attached to the eardrum called the ossicles, which vibrate the oval window that leads to the inner ear. This causes fluid in the chambers of the cochlea to move, vibrating the basilar membrane.
49.9K