Cellularization (original) (raw)

The theory of cellularization, also known as the syncytial theory or ciliate-acoel theory, is a theory to explain the origin of Metazoa. The idea was proposed by Hadži (1953) and Hanson (1977). The cellularization theory states that metazoans evolved from a unicellular ciliate with multiple nuclei that went through cellularization. Firstly, the ciliate developed a ventral mouth for feeding and all nuclei moved to one side of the cell. Secondly, an epithelium was created by membranes forming barriers between the nuclei. In this way, a multicellular organism was created from one multinucleate cell (syncytium).