The number of nerve cells in the cerebral cortex of man

In a normal brain fixed by perfusion, the number of nerve cells in the cortex was determined by counting the nucleoli in sections of measured thickness. The Abercrombie correction formula was used, and a mean value obtained of 17,560 cells per mm3. The linear shrinkage was determined in three other brains, both after fixation in alcohol‐formalin and after paraffin embedding and sectioning. A 20% shrinkage in volume was found after fixation, and a 74% shrinkage in volume after the histological procedures. Reckoning with a cortex volume of 570 ml in the unfixed brain, the total number of nerve cells in the cortex examined is found to be 2.6 × 109 cells.