MEAN VOLUME OF PIGMENTED NEURONS IN THE SUBSTANTIA-NIGRA IN PARKINSONS-DISEASE

A new unbiased stereological estimator, the rotator, was used to estimate the mean volume of pigmented substantia nigra (SN) neurons in three Parkinson's disease (PD) brains and agematched controls. Average pigmented neuron volume was 31300-mu-m3 (5200) in controls and 28900-mu-m3 (120) in patients. Estimating the absolute size distribution, revealed that PD patients had almost-equal-to 80% less total SN pigmented volume than controls. Compared with biased methods, in addition to dramatic improvements in efficiency and accuracy. results obtained by the unbiased rotator suggest that primarily the largest pigmented neurons in SN are lost in PD.