Expression of glycoconjugates in the human fetal cochlea.

The distribution of glycoconjugates in the human fetal cochlea was analyzed using six biotinylated lectins: wheat germ agglutinin (WGA), abrus precatorius agglutinin (APA), ulex europaeus agglutinin I (UEA-I), ricinus communis agglutinin 120 (RCA120), helix pomatia agglutinin (HPA), concanavalin A (ConA). The tectorial membrane (TM) in the 11- and 15-week-old human fetuses was labelled with WGA, APA, RCA120 and ConA, but not with UEA-I and HPA. In the 19-week-old fetuses, the reaction of the TM decreased. In the 11-, 15- and 19-week-old fetuses, the surface of the greater and the lesser epithelial ridges were respectively labelled with WGA, APA and RCA120. Reissner's membrane was labelled with WGA, ConA, APA, RCA120 and HPA. WGA, RCA120 and APA strongly stained the stria vascularis, especially in the 15-week-old fetuses. HPA did not stain the 11-week-old fetal cochleas at all, while it stained the apical surface of the hair cells, Reissner's membrane, the cells within the stria vascularis and spiral osseous lamina in the 15-week-old fetuses. In the 19-week-old fetuses, the fluorescent reaction with HPA became decreased and the apical surface of the hair cells was not labelled with HPA at all. This result suggests that HPA reactive glycoconjugates may be related to the molecule responsible for stereociliary adhesion only during development.