[Lissencephaly: agyria. A study using the Golgi technic].

A case of lissencephaly (agyria) is reported in which the Golgi stain was used to study the fronto-parietal cortex. The external cellular layer, the so-called true cortex, was shown to be made up of neurons from the 5th and 6th layers of the normal cortex. The neurons in the much less cellular layer were shown to be large pyramidal cells with well-developed dendritic branching and spines. The deeper cellular layer was a neuronal pool without well-defined layering. All the neural forms from the normal cortex were represented. In this layer the inner neurons showed a less advanced stage of development than did those in the outer groups. In the external cellular layer there was a disorganization of neuronal disposition as well. Otherwise typical large and medium-sized pyramidal cells from the outer third showed apical dendrites directed towards deeper structures, and the basal dendrites ran through the marginal layer. Neurons with doulbe dendritic branching and fusiform neurons were present in an abnormal rotated position. In both cases, the axons always showed a descending direction. These findings add to existing knowledge concerning the anatomy of the lissencephalic cortex, although the exact interpretation of the abnormalities found in the external cellular layer remains speculative.