The micrometer-scale self-assembly behaviour of MCM-41-type mesostructured silica is revealed through the study of a family of vesicular mesostructured silica with topology genus from 1 to 0 (see Figure and inside cover) The topological transformation and assembly kinetics demonstrate that the formation of the vesicular structure is closely correlated with the properties of the cetyltrimethylammonium-silicate building block and the hydrophobic nature of the ester additive.