Morphogenetic Movements

Abstract

The cellular architecture of the blastoderm is that of a simple monolayer. Embryonic development can, in short, be described as the process of transforming this bidimensional structure into the tridimensional structure of the young embryo, in which the basic body pattern (Seidel 1960, Sander 1976, 1983) can be recognized. Such a topological transformation is achieved by means of morphogenetic movements. Morphogenetic movements may take place either (1) by growth and infolding of certain regions of the monolayer, though maintaining the original topological arrangement, as it happens, for example, with the development of the epidermal anlage; or (2) by separation of cells or cell arrays from the monolayer into the interior of the embryo which thereby lose the original topological context, as happens, for example, with the mesoderm or the midgut.