Sexual Dimorphism in Volume of Parahippocampal Cortex in Normal and Neurodegenerative Subjects- A Stereological and Macroscopical Study

Purpose: This study is designed to determine the sex differences in volume of the left parahippocampal cortex in right-handed normal subjects and the right-handed subjects which were suffered from Alzheimer and parkinson diseases. Materials and Methods: This study was performed on 72 normal human brains (38 males, 34 females), 11 brains suffered from Alzheimer (4 males, 7 females), and 13 brains suffered from Parkinson (9 males, 4 females). The age range of males and females in each group were 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 for morphometrical analysis. Volume estimation of the left parahippocampal cortex was performed on photographs of 5mm serial coronal sections of this hemisphere by a point grid and using the Cavalieris principle. The results were " analysed by t-student and non - parametrical Mann - Whitney statistical tests. Results: The volume of the left parahippocampal cortex in right- handed normal males and females was 4.95 ±1.47cm3 and 4.01 ± 1.05cm3, respectively. The percentile difference in the volume of the left parahippocampal .cortex between two sexes was 18.99% (P=0.003).The volume of the left parahippocampal COrtexin right- handed males which were suffered from Alzheimer was 2.66 ±1.24cm3,and in right-handed females of this group was 2.61 ±1.18 cm3. The volume of the left parahippocampal cortex in right-handed . males and females which were suffered from Parkinson was 4.08 ±0.95 cm3 and 3.95 ±0.90cm3, respectively. The sexual difference in volume of the left parahippocampal cortex neither in AIzheimer nor in Parkinson group was significant. Conclusion: The volume of the left parahippocampal cortex in right - handed normal males is significantly larger than females. On the other hand, neurodegenerative diseases, such as Alzheimer and Parkinson, appearently decrease the normal gender difference in volume of the parahippocampal cortex, which can be due to more atrophy in this area of cortex in males than females.