1 Introduction  
2 Grid Cell Measures  
3 Development  
4 Topographical Organization  
5 Functional Properties  
5.1 Phase Precession  
5.2 Influence of External Cues  
5.3 Realignment  
5.4 Rescaling  
5.5 Influence of Environmental Geometry  
5.6 Fragmentation  
6 Neuronal Structure  
6.1 Neuron Morphology in the Entorhinal Cortex  
6.2 Topographical Organization and Microcircuits  
7 Conclusions