Scanning electron microscopy of lens placode invagination in the chick embryo

Abstract

The surface configuration of the chick lens placode at various stages of invagination has been examined by scanning electron microscopy. Distinctive differences between the exposed parts of its cells were observed in different parts of the placode which can readily be correlated with the invagination process. These findings are discussed in relation to mechanisms which have been proposed for the invagination of the lens placode and other embryonic rudiments whose development involves the conversion of a flat epithelial sheet into one that is curved or folded.