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Background&Objective: This study is designed to deteremine the sex differences in volume and surface anatomical parameters in the cingulate cortex of the left cerebral hemispheres in healthy right - handed subjects. Materials&Methods: This cross - sectional descriptive study was performed on 72 human brains (38 males, 34 females). The brains belonged to right - handed subjects who had died of non - neurologic causes. The age of males and females was similar. The brains were removed from the cranium no longer than 24 hours postmortem and were fixed in 4% formaldehyde solution. The right hemisphere of each brain was used for neuropathologic examinations (to confirm the health of the brain) and the left one was used for stereologic analyses. The estimation of the volume, surface areas, and thickness of the cingulate cortex was performed on photographs of 5 mm serial coronal sections of the left hemispheres using unbiased stereological methods (with point and linear grids). The results were analyzed by t- student test. Results: The volumes of the left cingulate cortex in males and females were 10.923.06 and 10.52.30cm3, respectively. The outer surface area was 43.8710.73 cm2 in males and 43.748.68cm2 in females. The inner surface areas in males and females were 34.8711.56 and 36.558.08cm2, respectively. There was no significant difference between two sexes in the volume and surface areas of the left cingulate cortex. The mean thickness of the left cingulate cortex in males and females were 2.880.5 and 2.510.3mm, respectively. The mean thickness of the left cingulate cortex in females was 12.85% smaller than males (P<0.05). Conclusion: Although the volume and outer and inner surface areas of the left cingulated cortex are similar between two sexes, the cortical thickness of this area in healthy right - handed females is significanlty smaller than males. The functional significance of these sexual differences and similarities in human brain is not clear. However, scientists must be aware of them in their morphometrical studies on human brain.

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Background&Objective: Lead toxicity is a common popular problem. Many researches were performed about this toxicity both in-vivo and in-vitro since 100 years ago.Those studies showed that lead have toxic effects such as behavioral disorders, decrease of IQ and decrease of learning and memory. Also lead has neurotoxic effects such as decrease of neuronal density in visual cortex of monkey, cell death in hippocampus and decrease of acetylcolin in rat’s hippocampus. In this study we examin neurotoxic effects of lead on rat’s radial nerve because radial nerve is a mix nerve. Materials&Methods: 24 adult male rats were divided in six groups. Groups I and II received lead acetate 4% and 2%, groups III and IV received disttiled water and normal water for one month.After this time, we killed rats and exposed radial nerve from behind of arm.Then studied them with light and electron microscopy. Results: In experimental groups we saw decrease of myelin sheath diameter and decrease of nuclear density in schwann cell. Also we saw many granules in mitochondrial matrix, active macrophage, edema and disarrangement of myelin sheath layers. Conclusion: We suggest that lead neurophaty is due to schwann cell injury and this lesion lead to decrease of myelin sheath.