The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance. In mammals, it consists of the bony labyrinth, a hollow cavity in the temporal bone of the skull with a system of passages comprising two main functional parts:
In a laboratory setting, HIV has been kept alive for as long as 15 days after the body fluid has dried, but this was controlled at a stable temperature and humidity that would be nearly impossible to reproduce in the natural world.
HIV infection goes into its second stage, which can be a long period without symptoms, called the asymptomatic (or latent) period. This is when people may not know they are infected and can pass HIV on to others. This period can last 10 or more years. During this period without symptoms, HIV is slowly killing the CD4 T-cells and destroying the immune system. Blood tests during this time can reveal the number of these CD4 T-cells. Normally, a person has a CD4 T-cell count between 450 and 1,400 cells per microliter.