Laminin in the endolymphatic sac and vestibular endorgans of developing chick embryos

The expression of laminin was analyzed in the vestibular endorgans of chick embryos using immunohistochemical methods. The basement membrane of the otocyst in the 5-day-old chick embryo was positive for laminin. In the 9-day-old chick embryo, the basement membrane of the macula of the saccule and utricle was positive, but the crista ampullaris showed a very weak positive reaction. The basement membrane of the endolymphatic sac in the 11-day-old chick embryo was strongly positive. These results suggest that laminin may be an essential substance with regard to the pathology of the vestibular endorgans. Moreover, the uneven distribution of laminin suggests that the basement membrane plays a role whose importance is yet to be determined in the physiology of the inner ear.