BIOSYNTHESIS OF CHOLESTEROL 



399 



during the latter half of incubation was demonstrated by Stokes et al.^''^ 

 The largest porportion of conversion occurred in the embryo proper. Fur- 

 ther confirmation of the remarkable degree of synthesis of cholesterol from 

 acetate in the egg yolk was adduced by O'Donnell and Heard^^° and by 

 Schwenk.^^^ Figure 2 indicates the relative activity of the cholesterol 

 and of the fatty acids of neutral glycerides of egg yolk in the eggs obtained 



WEEKS 



Fig. 2. The incorporation of C^^ into the egg j'olk cholesterol and fatty acids of the 

 natural fat of a hen given acetate-l-C'* on the first day of the test.^*^ 



from a hen over a nine-day period following the intraperitoneal injection 

 of acetate-l-C^* in three doses over a period of twenty-four hours, with a 

 total of 1.43 X 10^ counts. 282 



2" W. M. Stokes, W. A. Fish, and F. C. Hickey, /. Biol. Chem., 200, 683-689 (1953). 



28" V. J. O'Donnell and R. D. H. Heard, Chemistry in Can., 4, No. 5, 58 (1952); cited 

 by R. D. H. Heard et al.. Recent Progr. Hormone Research, 9, 383-40 (1954), p. 394. 



2*^ E. Schwenk, Personal communication cited by R. D. H. Heard et al.. Recent Progr. 

 Hormone Research, 9, 383-410 (1954), p. 394. 



282 R. D. H. Heard, R. Jacobs, V. O'Donnell, F. G. Peron, J. C. Saffran, S. S. Solomon. 

 L. M. Thompson, H. Willoughby, and C. H. Yates, Recent Progr. Hormone Research, 9, 

 383-410(1954). 



