Changes in brain and sciatic nerve composition with development of the rhesus monkey ( macaca mulatta)

Abstract

We determined the composition of the brain and sciatic nerves of 135 rhesus monkeys (Macaca mulatta) ranging from 58 days gestational age to over 10 years. The period of most rapid increase in size is prior to birth, and at birth the brain is about 70% of adult size. The patterns of change in weight, protein, and DNA of the cerebellum indicate that this area matures later and grows more rapidly than the remainder of the brain. The concentrations (per gram wet weight) of protein increase at all sites in the brain, but those of DNA decrease during the period of most rapid growth. The concentrations of all lipids, particularly those most characteristic of myelin, were much higher in pons, cervical cord, and sciatic nerve than in cortical gray matter. The concentration of those lipids most typical of myelin were essentially absent from the pons at 100 days of gestation, reached more than one-half of adult values at birth, but continued to increase after one year. Cerebrosides and sulfatides most nearly followed that pattern in the pons. The concentrations of sphingomyelin, plasmalogen forms of phosphatidylethanolamine, and cholesterol were the next best indicators of myelination, whilst the concentrations of combined phospholipids, lecithin, phosphatidylserine, and diacyl phosphatidylethanolamine changed less than the first two classes of compounds.