One of the significant challenges in the modelling of grain growth is the link between 3D models and their 2D simplifications.In the present study a 3D model of grain growth has been investigated which takes into account change in volume of individual grains randomly sampled from a population of a given initial size distribution. For different kinetics of growth, changes in the size of grain sections are studied. The fictitious effect of the generation of new grains in a 2D approximation of 3D growth (due to the growing grains hitting the observation plane) has been studied in detail. The influence of different types of initial grain size distributions on the grain growth has been investigated.