Lipid composition of gray and white matter in developing rat brain.

The lipid composition of gray and white matter was studied in the developing rat brain. For this purpose, gray and white matter were separated from the brains of rats from different age groups and were used for the estimation of moisture and lipids. The moisture content of both gray and white matter decreased with age, but the decrease was more significant in the latter. The concentration of different lipids in gray matter reached adult values at 4 weeks of age, whereas the lipids in white matter showed a slower increase even after this period. Similarly, the content of gray matter reached adult values much earlier (by 3 weeks) than white matter, which continued to increase throughout the period of study. Myelin represented 40% of the dry weight of whitematter. The non-myelin portion of white matter had a different lipid composition than gray matter, white matter, or myelin.