[Morphometric studies of prepyramidal and pyramidal neurons of various vertebrates].

Praepyramidal and pyramidal neurons were demonstrated in homologous telencephalic areas of Salmo irideus (Gibbons 1855), Rana temporaria L., Rattus norvegicus, forma alba, by means of the Golgi-technique. A comparative morphometrical analysis was made concerning the following parameters: main dendritic length, length of the pericaryon, number of dendritic spines in the first 50-micrometer-dendritic segment and length of the spines-free zone. From these data a quotient was calculated and expressing the theoretical dendritic length per ten spines. There is an increase of length of the pericaryon, length of the spines-free zone, main dendritic length and a pseudo-decrease of the number of dendritic spines in the first 50 micrometer-dendritic segment in rats, as compared with Rana and Salmo. The results are discussed with respect to following problems: homology, phylogenesis and corticalisation.