  We investigate morphologies of proliferating cellular tissue using a newly
developed numerical simulation model for mechanical cell division. The model
reproduces structures of simple multi-cellular organisms via simple rules for
selective division and division plane orientation. The model is applied to a
bimodal mixture of stiff cells with a low growth potential and soft cells with
a high growth potential. In an even mixture, the soft cells develop into a
tissue matrix and the stiff cells into a dendrite-like network structure. For
soft cell inclusion in a stiff cellular matrix, the soft cells develop to a
fast growing tumour like structure that gradually evacuates the stiff cell
matrix. With increasing inter-cell friction, the tumour growth slows down and
parts of it is driven to self-inflicted cell death.
