Brain weight: what does it mean?

The weights of the whole and various parts of 8 unfixed normal adult brains were determined at autopsy, and the relative weight of each part as compared with the total brain weight was calculated. On the average, the cerebrum accounted for 87% of the total brain weight, the cerebellum and brain stem for 13%, whereas the contribution of the attached upper spinal cord was negligible (< 2 g). The removed leptomeninges had a mean weight of 34.2 g (2.5% of the total brain weight), but they may reach 50 g. The slices of the cerebrum with removed leptomeninges weighed only 79.2 - 84.4% of the total brain weight. It is concluded that all scientific papers reporting brain weights should state whether the recordings are based upon fresh or fixed specimens and, in the latter case, the fixation procedures must be described accurately. Furthermore, it is of equal importance to indicate exactly the anatomic structures that have been weighed.