The image above shows the inner ear of a mouse, including the organ of Corti, the looped strip of cells inside the ear that transduces sound vibrations into nerve impulses, and inside it the vestibular sensory epithelia, which are tiny sensory hairs that aid hearing and balance.
The image was taken as part of study of an experimental gene therapy for a condition known as Usher syndrome, which causes people to be born profoundly deaf and without a normal balance function. Usher syndrome is caused by mutations in the gene that produces a protein called SANS which is vital for the cohesion of the hairs in the inner ear.
The experimental therapy introduced a functioning copy of the gene into the inner ears of Usher syndrome mice using the harmless AAV8 virus as a vector. In the image above, the cells producing proteins from the introduced gene are tagged in green and orange.