The cyto- and fibroarchitectonics of areas 8, 10, 32/10, 44, and 45 of the frontal cerebral cortex were studied at intervals of one year using computer morphometry. It was established that the dimensional parameters of the neuronal groups of the ensemble-forming layer III and the neuron to fiber specific volume ratio are informative parameters for studying the specific features of the ensemble organization of the frontal cortex in postnatal ontogeny at the cellular population level. It was shown that it takes the associative areas 44, 45, 10 of the lateral prefrontal zone long to develop in the process of ontogeny: the most important structural transformations occur stage by stage and are observed during the first year of life, as well as at the ages of 3, 6-7, 10, and 13-14 years. © Pleiades Publishing, Inc., 2010.