ABSTRACT
The rat's body, total brain, forebrain and cerebellar weights were recorded in 2, 5, 12 and 24 months old animals. The ratios between brain and body weights as well as cerebellar to forebrain weights were examined. The statistical tests showed a significant increase in the body, total brain and cerebellar weights from 2 to 24 months of age. The forebrain weight showed an increase between 2 and 5 as well as 5 and 12 months and a insignificant difference between 12 and 24 months of age. The brain to body weight ratio showed a significant decrease with age in all age groups indicating a slower increase in the brain weight as compared with the body weight with age. Cerebellar to forebrain weight ratio showed a significant increase between 12 and 24 months of age reflecting the stoppage of any increase in the forebrain weight during this period of life, while the cerebellar weight was still increasing. This was attributed to the post-natal origin of the cerebellar granule cells, which were suggested to survive when the death of other neurons occurred