New stereological techniques, superior to conventional methods in quantitating macroscopic and microscopic structures in the central nervous system, have been developed within the last decade. By the use of a new counting method, the dissector, it is possible to obtain an efficient and yet precise estimate of the total number of neurons in any specific region, where a delineation of the region can be made, and the cells identified. The method has been applied to brains from patients with different neurological disorders. The latest effort has concentrated on the estimation of the total neocortical neuron number in brains from normal individuals of both sexes in the age from 20 to 90 years to see whether there are differences in total neocortical neuron numbers between males and females.