Increase of the neuron number in some cerebral cortical areas of a lizard, Podarcis hispanica, (Steind., 1870), during postnatal periods of life.

Neuronal counts in the medial, dorso-medial, and dorsal areas of the cerebral cortex of a common lizard, Podarcis hispanica, have been performed on a set of different sized (aged) animals. With age, (size), there is a significant increase in the number of neuronal somata of the inner plexiform and granular strata of both the medial and dorso-medial areas. In the granular stratum of the medial cortex, this increase appears to be mostly due to addition of small somata, whereas in the granular stratum of the dorso-medial cortex, the increase must be due to addition of large somata. The dorsal cortex does not show a conspicuous increase in itscell population, but postnatal development implies aggregation in "clusters" of some neuronal somata of the inner plexiform layer. The postnatal increase of neurons in the cerebral cortex of this lizard is correlated with the postnatal appearance and growth of both the dorso-medial area and the septocortical Timm's positive system of axonic endings of this species, close similar to the hippocampal mossy fiber system of Mammals.