Sexual Dimorphism in Volume of Precentral Cortex of Human Brain in Normal Subject who are Suffering from Alzheimer and Parkinson-A Stereological and Macroscopical Study

Purpose: This study is designed to determine the sex difference in volume of precentral cortex of left hemisphere in right-handed normal subjects and the right-handed subjects which are suffering from Alzheimer and Parkinson diseases. Materials and Methods: This study was performed on 72 normal human brains (38 males, 34 females), 11 human brains suffering from Alzheimer (4 males, 7 females), and 13 brains suffering from Parkinson (9males, 4 females). The age range between males and females in each group was similar. The brains were fixed in 4% formalin.The brainstem was removed and two hemispheres were separated by a midsagittal section. The right hemisphere was used for neuropathological diagnosis and the left one was used for morphometrical analyses. Volume esimation of the precentral cortex of left hemisphere is performed on photographs of 5mm serial coronal sections of this hemisphere using the Cavalieri's principle and point counting. The results were analysed by t-student and non-parametical Mann-Whitney Statistical tests. Results: The volume of left precentral cortex had no significant sexual difference in any of three groups (normal, Alzheimer, and Parkinson groups). There was only a tendency for this parameter to be larger in males than females in normal and Parkinson groups. Conclusion: Although the volumes of left hemisphere and its frontal cortex are larger in normal men, there is no significant difference between two sexes in volume of precentral cortex. Therefore, the sexual dimorphism in volume of frontal cortex in normal group may be due to other subdivisions of this lobe, except than precentral gyrus.