Colloquium: Mechanical formalisms for tissue dynamics Sham Tlili, Cyprien Gay, François Graner, Philippe Marcq, François Molino and Pierre Saramito Eur. Phys. J. E, 38 5 (2015) 33 Published online: 13 May 2015 DOI: 10.1140/epje/i2015-15033-4