[Quantitative histological studies of lamina V and lamina III pyramidal neurons in the motor cortex of the rat. The question of laterality].

Laterality of several brain functions has been demonstrated in the human brain cortex as well as in several animal species indicating an evolutionary genesis of the brain's asymmetry. To get some morphological data, we investigated Golgi impregnated pyramidal neurons in lamina III of regio precentralis agranularis of the major cortex from adult rats. The spine number and density and the length of the dendrites forming a basal or apical single dendritic field (SDF = EDF) of these neurons were estimated. The statistical significance of the data was proved by comparing the neuronal parameters obtained from the right or left hemisphere of the same animal (individual laterality), as well as by testing the mean values from right or left cortex of several animals (species laterality). However, in both cases no statistical significance could be obtained. From these results two conclusions should be drawn: Firstly, the parameters in a single dendritic field of cortical pyramidal neurons of both brain sides are statistically equivalent and not asymmetrical developed. Secondly, the single dendritic field of cortical pyramidal neurons can not serve as a morphological counterpart for functional asymmetries in the rat brain. Here, further interdisciplinary research is necessary.