Size comparison of the male and female human corpus callosum from autopsy samples

161 cases of human-brain autopsies (93 Male, 68 Female) were collected from three samples in the Kinai district of Japan. From photographs of the midsagittal plane of each brain, surface areas of the corpus callosum (CC in mm2) and of the medial view of the cerebrum (H in mm2) were measured. The absolute H and CC values from each of the three samples were larger in males than in females, with full overlapping of the male and female ranges for both H and CC values. However, the relative values of CC corrected for H (CC/H) were almost equal between sexes. The relative values for the posterior one-fifth (splenium) of the CC, which were divided by CC or H, were slightly higher in females than in males in each of the three samples, but without statistical significance. This trend was also found in the relative values for the posterior one-third of the CC and in the relative values for region, meaning the posterior one-fifth of the CC subtracted from the posterior one-third of the CC (isthmus), but not in the relative values for the anterior one-fifth (genu) of the CC.