Enzymatic activities in mitochondria isolated from the rat brain during development.

In an attempt to discern whether mitochondrial changes during ontogeny are due to increases in number of mitochondria or to increases in number plus changes in their organization, we investigated the enzymatic markers of the inner and outer membranes of mitochondria from cerebral cortex and subcortical material in young and adult rats. We conclude from the data gathered that significant changes do occur in mitochondrial organization, that gradual maturation occurs in the inner membrane during development, especially in the cerebral cortex and considerably less so in the subcortical structures. We found no such changes in the sturucture of the outer membrane during the periods of development examined.