| Abstract: |
In most literatures, much controversy are evident regarding the exact age period at which the corpus callosum reach its full maturity and whether a sexual dimorphism in the development of the callosum or not. This paid the attention of studying the callosal development in both sexes and in different age groups using MRI. This imaging technique is a save and a reliable method for accurate visualization and hence measurement of the midsagittal area of the corpus callosum and its subregions.In the present work, 200 neurologically normal individuals of both sexes, including 100 males and 100 females aged from 8 months to 70 years underwent midsagittal MRI scans of the brain. These subjects were classified into ten age groups, each of which included 20 subjects (10 males and 10 females).Regarding the age-related changes of the antero-posterior diameter of the corpus callosum and that of the medial aspect of the cerebral hemisphere, in the present study, they showed a linear growth up to the age of 18 years then the development is plateaued until 70 years. However, the linear index showed no statistical significant age-related changes from 8 months to 70 years.Also, it was found that the area of the corpus callosum and that of the brain in both sexes, it was found that the area of the callosum, its subregions and the midsagittal surface area of the cerebral hemisphere showed a spurt of growth between 8 months and 6 years of age, then the growth went linear up to the age of 18 years (except the genu that proceeded to 24 years).Then the growth became stationary until 60 years. After the age of sixty these parameters decreased.The possible explanation of age-related increase in the length and the area of both cerebral hemisphere and that of the corpus callosum was mostly due to more neurogenesis, more proliferation of neuronal synapses, arborization of cerebral neurons and myleination process. However, the decline in these measurements upon aging could be explained by the physiological brain atrophy.Considering, the sex-related changes in the antero-posterior diameter of both the corpus callosum and the medial aspect of the cerebral hemisphere, it was found that no statistical significant sex difference in the age period between 8 months and 2 years of age. However, between 2-70 years these parameters were higher in males than their corresponding mean values in females. However, the linear index showed no sex difference.Moreover, no sex difference was evident as regard the total callosal area and the areas of the rostral body, midbody and isthmus. While, the genu, and the cerebral hemisphere were greater in males than in females. but the area of the splenium and the callosal index was greater in females than in males.The sex difference in the measured parameters is mostly related to difference in the sex hormone receptors in the brain and/or difference in brain lateralization between males and females.
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