[Asymmetry and sexual dimorphism of the medial frontal gyrus visible surface in humans].

BACKGROUND/AIM: Studies of visible (extrasulcal) surface of the brain hemispheres are not feasible for measurements of the brain size, but are valuable for analysis and quantification of sexual dimorphism and/or asymmetries of the human brain. Morphological and morphometric investigations of the brain may contribute in genetic studies of the human nervous system. The aim of this study was to determine and to quantify sexual dimorphism and the right/left morphological asymmetry of the visible surface of medial frontal gyms (gyrus frontalis medialis - GFM).

METHODS: Measurements and analysis of the visible surface of GFM were done on 84 hemispheres (42 brains from the persons of both sexes: 26 males and 16 females, 20-65 years of age). After fixation in 10% formalin and dissection, digital morphometric measurements were performed. We studied these in relation to the side of the hemisphere and the person's sex. Standardized digital AutoCAD planimetry of the visible surface of GFM was enabled by the use of coordinate system of intercommissural line.

RESULTS: In the whole sample, the visible surface of the right GFM (21.39 cm2) was statistically significantly greater (p < 0.05) than the left GFM (18.35 cm2) indicating the right/left asymmetry of the visible surface of GFM. Also, the visible surface of the right GFM in the males (22.66 cm2) was significantly greater (p < 0.05) than in the females (19.35 cm2), while the difference in size of the left GFM between the males and the females was not significant (p > 0.05).

CONCLUSION: Morphological analysis of visible surface of GFM performed by digital planimetry showed sexual dimorphism of the visible surface and the presence of right/left asymmetry of GFM.