[The individual variability of pyramidal neurons in the neocortex of the rat]

In Golgi-Kopsch impregnated pyramid neurons of the neocortex (regio precentralis agranularis and area striata) of adult rats the individual variability was investigated. As parameters served the dendritic lengths, spine numbers and spine densities along the dendritic orders (basal and apical), within single dendritic fields, the apical and basal parts of the dendritic tree and of the whole neuron. The statistical tests gave the following results: Pyramid neurons in the regio precentralis agranularis are more variable than pyramid neurons in the area striata. Within the area striata the lamina III-pyramid neurons are more invariable than the lamina V-pyramid neurons. The basal dendrites are statistically more invariable than the apical dendrites. The dendritic lengths are less variable than the spine values. In general, the variability is different in particular subdivisions of the neurons analyzed as well as for the parameter chosen. The variability of neuronal structures depends from genetical factors and from a functional training. The knowledges about this variability are still insufficient. They are of considerable importance for the planning of experiments followed by statistical analyses.