Brain-to-body ratios and time of maturation of the mouse brain

Abstract

Studies on the relationships of brain weight to body weight during development were conducted in 218 mice, and revealed three distinct phases. During the first phase, the ratios are relatively constant. The second phase of short duration is characterized by abrupt reductions. In the third phase, which is the most enduring, the ratios again assume more constant values. The abrupt change in the ratios took place around 14 days of age. It is suggested that the abrupt change in the ratio is, in general, an indicator of the maturation of the brain, because there are several other parameters which approach mature levels around the 15th day. A review of the data on other species supports this suggestion.