Quantitative study of DNA contents (cell numbers) in parts of the rat brain.

DNA contents (cell numbers) of rat brain parts were determined for cerebral hemispheres, cerebral cortex, cerebellum, and brain stems at postnatal ages 30, 60, 90, and 120 days. It was found that for all these parts these contents reach their maxima (maturation plateaux) at the same age (weaning; 30 days). Thus, cells in these brain parts attain mature numbers in concert. The significance and the possible mechanisms to achieve such close synchrony are discussed.