Development of the Organ of Corti of the Newborn Mouse in Culture

Abstract

Differentiation and afferent innervation of the organ of Corti were studied in 152 cultures. If an unopened turn of the cochlear duct and its complement of spiral neurons are explanted, the culture retains the compact arrangement of innervated hair cells which are the only differentiated elements at birth. During the following two weeks in culture supporting elements, reticular plate, and tunnel spaces differentiate. Development of tectorial membrane is observed. Innervation pattern in a differentiated culture is basically similar to that at birth even though the innervation derives only from locally present neurons. Fibers collect into radial bundles; some terminate immediately upon the inner hair cells; others form the inner spiral band; still others cross the tunnel to form external spiral fibers. Different events occur at injured edges, or in entire explant if during explantation the cochlear duct is torn. No differentiation of supporting cells occurs. Hair cells spread outward, acquiring a ghost-like appearance. Nerve fibers follow the degenerating cells and may form spirally oriented bundles. Some leave the disorganized hair-cell region, growing freely for several millimeters. [Supported by USPHS Grants NS-08626, NS-03360, and NS-06225.]