The Mammalian Cochlea

A marked differentiation between the outer and inner hair cells is one of the characteristics of the mammalian cochlea. These two groups of cells are separated by Corti's tunnel, which is presumably filled with Corti's lymph. Communication between Corti's tunnel and the scala tympani is thought to be accomplished by Schuknecht's channel, the presence of which in mammals was confirmed in the present study. It was also confirmed that the endolymphatic spaces of fresh frozen mammalian cochleae are filled with proteinaceous (or fibrillar) material(s), as reported by A. Flock. Mammalian sensory hairs are unique in their arrangement and in the loss of kinocilia as the organ of Corti matures, in contrast to the sensory hairs of other animal classes, which are strikingly similar to the mammalian vestibular sensory hairs. The mammalian outer hair cell sensory hairs are firmly attached to the tectorial membrane, but it is controversial whether the inner hair cell sensory hairs are likewise attached. The physiological significance of this arrangement and the cyto-archi-tecture of the mammalian organ of Corti are discussed. In addition, the stria vascularis, the spiral limbus, and Reissner's membrane, which are implicated in the production and/or maintenance of endolymph, are discussed.