Visual functions undergo an age-related degradation. However, the neural mechanisms underlying these changes are not yet clear. This study was designed to investigate the influence of age and sex on the anatomy of the rat＇s visual cortex. Dendritic tree extent and spine density were examined in young adult rats （2-3 months） and aged male and female rats （22-24 months） using a modified Golgi-Cox staining method. A sex difference in dendritic branching of the pyramidal cells was found among young adults. However, this difference disappeared during aging, due to a reduction in branching with age for males but not for females. Moreover, the pyramidal cells of young males also have a greater spine density. Although there was a reduction in spine density with age for both sexes, this reduction was more pronounced for males, resulting in a disappearance of sex difference with age. Thus these results suggest that aging could lead to the degeneration of dendrites, which might contribute to the degradation of age-related visual functions. Also the results indicate that age-related degeneration of dendrites is more severe for males than for females.
