Sex Differences in the Cerebellum and its Correlates with Some Body Traits in the African Grasscutter (Thryonomys swinderianus – Temminck, 1827): Morphometric Study

　Introduction: Sexual dimorphisms in biological structures such as brain and behaviour have been widely recognized in animals and humans. The purpose of this study was to examine whether there are sex differences in the size of the cerebellum with other body traits, such as the head, tail and brain. Methods: Twelve grasscutters comprising of 6 males and 6 females were used in this study. Each brain was extracted from the skull by standard procedures and the mean values of the weights, dimensions and volumes of the brain, cerebellum, head and tail were compared in male and female using quantitative analytical statistical method. Results: The results showed that the absolute mean brain weight and volume obtained in the male was slightly higher than that of the female, while the cerebellar mean weight was slightly higher in the female although these values were not statistically significant (P> 0.05). The mean cerebellar lengths and widths did not differ between the two sexes (> 0.05), but the mean cerebellar circumference in the male was statistically higher than in the female (P< 0.05). The female cerebellar length was positively correlated with the length of the brain, head, body and tail. Discussion: In conclusion, the brain weight was slightly higher in the male than female, while the cerebellar weight was higher in the female than male. The significantly higher value of the cerebellar circumference in the male may partly be responsible for the big round head seen in the live male grasscutter.