778 VII. LIPID DISTRIBUTION IN SPECIFIC TISSUES 



sterol proportion remains uniform in those divisions of the outer layers in 

 which keratinization processes are absent, the ratio decreases in the outer 

 layers in which keratinization is taking place. In the latter regions, phos- 

 pholipids are apparently destroyed, but less destruction of cholesterol 404 

 takes place. Since no phospholipids are present in the hair division, a 

 more rapid destruction of phospholipids than of cholesterol takes place at 

 the skin surface. 



Taylor et al. m noted that a sex variation occurred in the lipid composition 

 of rat skin. Total lipids made up 22% of the dry weight in the female 

 skin, and only 12.5% in that of the male rat. On the other hand, total 

 cholesterol was higher in the skin tissues of the male (0.354%) than in those 

 of the female (0.248%), but free cholesterol was higher in the female 

 (0. 132%) than in the male (0. 1 18%) . 



Roffo 407 reported that the cholesterol content of the skin of men is greater 

 than that of women. It is suggested that the higher susceptibility of men 

 to cutaneous neoplasm, especially of the face, may be related to this phe- 

 nomenon, inasmuch as neoplasms contain more cholesterol than does 

 healthy, normal tissue. 



The cholesterol content varies with the particular area of the skin in- 

 volved. Roffo 407 - 408 reported that the cholesterol content of skin from an 

 exposed area such as the face was greater than in that obtained from an 

 area normally covered, such as the abdomen. In the case of the adult, 

 more cholesterol occurred in the skin of the face than in that of the back; 

 this was also the case in the skin of the fetus or newborn, but to a consider- 

 ably lesser degree. 409 The cholesterol in the facial skin of the infant was 

 shown to increase with age, as a result of the effect of light. 409 Thus, 

 Roffo 410 - 411 found that irradiation of the skin with sunlight caused an in- 

 crease in the cholesterol content of rat skin, while a decrease occurred in 

 the skin content of this sterol when the animals were kept in the dark. 411412 

 Kawaguchi 413 reported that an increase in skin cholesterol also resulted in 

 guinea pigs and rabbits subjected to ultraviolet irradiation, although the 

 response was not as marked as that to sunlight. Roffo 407 - 408 found a rela- 



406 J. D. Taylor, H. E. Paul, and M. F. Paul, Arch. Biochem., 17, 421-428 (1948). 



407 A. H. Roffo, Nioplasmes, 7, 344-351 (1928). 



408 A. H. Roffo, Bol. inst. med. exptl. estud. cdncer (Buenos Aires), 6, 370-382 (1929); 

 Chem. Abst., 26, 1304 (1932). 



409 A. H. Roffo, /. physiol. et pathol. gin., 30, 345-349 (1932). 



410 A. H. Roffo, Bol. inst. med. exptl. estud. cdncer (Buenos Aires), 8, 32-38 (1931); 

 Chem. Abst., 29, 5871 (1935). 



411 A. H. Roffo and F. Pilar, J. physiol. et pathol. gin., 28, 854-856 (1930). 



412 A. H. Roffo, /. phrjsiol. et pathol. gin., 29, 739-741 (1931). 



413 S. Kawaguchi, Biochem. Z., 221, 232-240 (1930). 



