The Early Development of the Otic Vesicle in Staged Human Embryos

Abstract

Ever since Huschke first recorded, in 1831, that the membranous labyrinth develops from the surface ectoderm (Streeter, 1918), a number of studies of otic development have been made (as reviewed by Altmann, 1950). The introduction during the present century, however, of embryonic staging in all vertebrate classes, and its use especially during the past two decades, have enabled precise correlations of morphogenesis and histogenesis with external embryonic appearances to be made. In the opinion of the present writer, the term ‘stage’ should not be utilized unless a staging system has been employed, and particularly not where mere time or measurements have been used. Expressions such as ‘the 39-day stage’ or ‘the 18-mm. stage’ are thus to be deprecated. In the present study of the otic vesicle, particular attention has been directed to the basement membranes, which have been almost totally ignored in previous accounts both of the developing, and indeed even of the adult, labyrinth.