In order for mammals to hear, sound vibrations travel through a hollow, snail shell-looking structure called the cochlea
. Lining the inside of the cochlea
are two types of sound-detecting cells, inner and outer hair cells, which convey sound information to the brain.
Although the neonatal cochlea
holds the potential to form new hair cells by transforming the supporting cells (such as Lgr5+ cells) into the hair cells in the apical till basal region [3-6].
After the temporal bones were decalcified, the otic capsule surrounding the cochlea
was asymmetrically dissected from the base to the apex using a stereo microscope (Olympus 1x71 S8-F3, Tokyo, Japan).
To identify transplanted cells in guinea pig cochleas
, mIESCs were transduced with a lentiviral vector carrying the lacZ gene (Plasmid 12108 Mammalian Expression, Lentiviral; Addgene, USA).
A new MRI, as interpreted by a head and neck radiologist, demonstrated left-sided T1-weighted hyperintensity in the basal turn (figure 1) and the middle turn of the cochlea
, as well as in the vestibule and in the semicircular canals.
After ABR measurement, the guinea pigs were immediately decapitated, and the bilateral temporal bones, open acoustic capsules, and cochleas
The procedure was abandoned and a subsequent high resolution CT scan showed complete ossification of the left cochlea
and but a patent cochlea
on the right (Fig.
To test the idea, Darlene Ketten, a biologist at Woods Hole Oceanographic Institution (WHOI), and WHOI researcher Julie Arruda provided high-resolution CT scans, taken at the WHOI Computerized Scanning and Imaging Facility, of cochleas
from 13 different land and mammal species.
Then, a long-term study on 26 ears found that all cochleas
had an increase in click-evoked auditory brainstem response thresholds for the first 4 weeks.
The first part of the cochlear implantation process involves the surgical procedure, when surgeons implant a small electrode into the snail-shaped cochlea
. About a month after the operation, an external piece of equipment is placed; it has a microphone that picks up sound and a processor that converts sound into coded electrical signals that are passed on to the implanted electrode.
Miyamoto is referring to cochlear implants--a revolutionary technology that can be used when the snail-shaped organ in the inner ear called the cochlea
Honjo, "Inhibition of Notch/RBP-J signaling induces hair cell formation in neonate mouse cochleas
," Journal of Molecular Medicine, vol.
Researchers at Genentech in South San Francisco now report that they've grown new hair cells in tissue taken from newborn rats' cochleas
. The scientists used fresh supplies of a gene, Math 1, to promote hair cell growth.
Over the next 10 days, the damaged area gradually returned to normal, and the thymidine tracer turned up in the damaged area in the nuclei of both hair cells and supporting cells but not in undamaged regions of the chicks' cochleas
-- the affected inner-ear structure -- or in chicks that received the tracer but were not subjected to loud noise.
Deafness often results from the loss of specialized nerve cells--called hair cells and spiral ganglion neurons--in the cochlea
, the part of the inner ear that converts vibrations into signals that the brain understands as sounds.