Type II collagen distribution in the ear of the developing chick embryo.

The localization of type II collagen was immunohistochemically studied in the developing chick ear using monoclonal antibodies. Type II collagen appeared under the basal lamina of the otocyst from developmental stages 14 to 16. In the otic capsule, endolymphatic duct, and semicircular canal membrane, type II collagen appeared in stage 23 or 24. From stages 28 to 29, type II collagen appeared in the primitive columella, endolymphatic sac, and fibrocartilaginous plate. Type II collagen was first observed in the crista ampullaris, basilar membrane, macula sacculi, and utriculi in stages 30 and 31. Type II collagen was not detected in the endolymphatic sac beyond developmental stage 37 and the amount of type II collagen in the otic capsule and columella decreased after stage 40. The wide distribution of type II collagen in the inner ear throughout the development of the chick embryo suggests that this collagen may act as a basic structural component of the ear.