Epithelial differentiation in developing murine eustachian tube and middleear

Detailed information on how an epithelial differentiation occurred in the d eveloping eustachian tube and middle ear would be helpful in understanding both normal physiology and pathology of the tubo-tympanum. This study was u ndertaken to establish patterns of laminin and E-cadherin in the embryonic mouse eustachian tube and middle ear by use of immunohistochemistry at a st age when epithelial differentiation is taking place. This study was also de signed to clarify the role of the middle ear mesenchyme. During the develop ment of the eustachian tube, relatively high immunoreactivity to laminin wa s observed in the epithelium at gestational days 16 and 17, when the develo pments of ciliated and secretary cells were first observed. At the time of birth, in contrast to epithelium of the eustachian tube, epithelium of the middle ear cavity showed predominant expression of laminin and E-cadherin, These findings suggest that the expressions of laminin and E-cadherin may b e correlated with maturation of the epithelium in the eustachian tube and m iddle ear and that the epithelial differentiation of the developing murine eustachian tube and middle ear may be controlled by epithelial-mesenchymal interaction and cell-to-cell interaction.