Vertebrate hearing and balance are based in complex asymmetries of inner ear structure. Here, we identify retinoic acid (RA) as an extrinsic signal that acts directly on the ear rudiment to affect its compartmentalization along the anterior-posterior axis. A rostrocaudal wave of RA activity, generated by tissues surrounding the nascent ear, induces distinct responses from anterior and posterior...

Liposome nanocarriers (LPNs) are potentially the future of inner ear therapy due to their high drug loading capacity and efficient uptake in the inner ear after a minimally invasive intratympanic administration. However, information on the biocompatibility of LPNs in the inner ear is lacking. The aim of the present study is to document the biocompatibility of LPNs in the inner ear after intraty...

There are dozens of different myosin isozymes, though it's not clear why cells require such a diversity. These images of fluorescently-labelled hair cells from the inner ears of frog, guinea pig and mouse show the localization of actin (red at top left and bottom right) and of four different forms of myosin (green, except at bottom left, where myosin VI is labelled in red). Hair cells are the r...

OBJECTIVES/HYPOTHESIS Despite the advancement of concurrent chemoradiotherapy, inner ear symptoms such as hearing loss, tinnitus, or vertigo/dizziness are still experienced in irradiated nasopharyngeal carcinoma (NPC) survivors. This study utilized an inner ear test battery to assess the causes and sequence of inner ear deficits in irradiated NPC survivors with a mean interval of 10 years after...

Five different pathways are often suggested as important for bone conducted (BC) sound: (1) sound pressure in the ear canal, (2) inertia of the middle ear ossicles, (3) inertia of the inner ear fluid, (4) compression of the inner ear space, and (5) pressure transmission from the skull interior. The relative importance of these pathways was investigated with an acoustic-impedance model of the in...

Loss-of-function experiments in avians and mammals have provided conflicting results on the capacity of fibroblast growth factor 3 (FGF3) to act as a secreted growth factor responsible for induction and morphogenesis of the vertebrate inner ear. Using a novel technique for gene transfer into chicken embryos, we have readdressed the role of FGF3 during inner ear development in avians. We find th...

The mammalian inner ear forms from a thickened patch of head ectoderm called the otic placode. The placodal ectoderm invaginates to form a cup whose edges cinch together to establish a fluid-filled sac called the otic vesicle or otocyst. The progenitor cells lining the otocyst lumen will give rise to sensory and non-sensory cells of the inner ear. These formative stages of inner ear development...

The otic capsule initially appears as condensations of mesenchyme around the developing otocyst, and serves as a template for the subsequent formation of the endochondral bony labyrinth of the inner ear. While it has long been known that the epithelial otocyst influences the induction and chondrogenic differentiation of the otic capsule, factors involved in epithelial control of otic capsule ch...

Autoimmune inner ear disease is described as progressive, bilateral although asymmetric, sensorineural hearing loss and can be improved by immunosuppressive therapy. We showed that the inner ear autoantigen β-tubulin is capable of inducing experimental autoimmune hearing loss (EAHL) in mice. Immunization of BALB/c mice with β-tubulin resulted in hair cell loss and hearing loss, effects that wer...

Various cellular replacement therapies using in vitro generated cells to replace damaged tissue have been proposed as strategies to alleviate hearing loss. All such therapies must involve a complete understanding of the earliest steps in inner ear development; its induction as a thickened plate of cells in the non-neural, surface ectoderm of the embryo, to its internalization as an otocyst embe...