40 



METABOLISM IN CHANGED CEREBRAL ACTIVITY 



Age, years 

 Age, months 3 4 

 Months in utero(Hunnan) I. 2 3 '^ ' 

 3 5 7 9 



1 — \ — r 



12 24 36 



Days after birth (rat) 



4 8 12 16 20 



Chick embryo (age, days} 



Fig. 8. The increase in sphingomyelin in brain during growth 

 and development. O == rat, mouse, data from Folch (1955) and 

 Brante (1949). 9 = chick embryo, data from Mandel et al. 

 (1949). n = human cerebral cortex, data from Brante (1949). 



in the chick embryo the 1 2th-l 6th day of incubation . Since increase 

 in quantity alone is a normal accompaniment of growth such 

 rapidity oi increase is a distinguishing feature. Other phospho- 

 lipids increasing rapidly during this period include the acetal 

 phospholipids or plasmalogens. In the mouse brain plasmalogens 

 increase from 0-19% of the wet weight to 0-75% of the wet weight 

 between the 5th-30th day of age. In human grey matter the sum 

 total of phosphatidyl serine, phosphatidyl ethanolamine, diphos- 

 phoinositide and plasmalogens increased some threefold between 

 the time immediately before myelination and the adult stage. In 

 white matter the increase was sixfold (Folch, 1955). This increase 

 could be accounted for by an increase both in plasmalogens and 

 phosphatidyl ethanolamine. The full significance of such increases 

 is not fully understood. In so far as certain phospholipids such as 

 sphingomyelin are considered to be part of the myelin sheath rapid 



