LIPIDS PRESENT IN SKIN AND ITS APPENDAGES 785 



taining it uncontaminated with other materials present on the surface of 

 the skin. Koppenhoefer 403 prepared a fairly pure sample from steer skin, 

 by first removing the horny layer and later pressing out the oily secretion 



Table 22 

 The Composition of Sebum" 



Analytical value3 



Total Mol. Sapon. Iodine Acetyl Acid 



Component ami, % wt. No. No. value value 



Total lipids 100.0 — 154.8 32.6 — 10.1 



Fatty acid 57.4 249.1 — 27.3 74.9 — 



Unsapon. fraction 42 . 7 — — 36 . — — 



Cholesterol, total 14.4 — — — — — 



Cholesterol, esterified 13.7 — — — — — 



Phospholipids 4.0 — — — — — 



• Adapted from R. M. Koppenhoefer, /. Biol. Chem., 116, 321-341 (1936), p. 335. 



Table 23 

 The Calculated Average Composition of Human Forearm Sebum" 



Per cent of 

 Component of sebum total lipid 



Free fatty acids 



Saturated 15.0 



Unsaturated 15.0 



Triglycerides 32.5 



Waxes (including cholesterol esters) 15.0 



Sterols 



Free cholesterol 2.5 



Combined cholesterol 6 (2.5) 



Other sterols 2.5 



Squalene 5.0 



Paraffins 7.5 



Unidentified compds. (including oxidized squalene) 5.0 



a Adapted from V. R. Wheatley, Livre jubilaire, 1901-1951, de la Societe Beige de 

 Dermatologie et de Syphilographie, 91-103; Imprima m6d. sci., Brussels (1952); cited by 

 R. P. Cook, "Comparative Aspects of Lipid Absorption and Excretion," in R. T. Wil- 

 liams, Lipid Metabolism, Biochem. Soc. Symposia, No. 9, 14-36, Cambridge Univ. Press 

 (1952). 



b Included in waxes. 



from the exposed sebaceous glands. Table 22 lists data on the composition 

 of sebaceous secretion obtained from steer skin, while Table 23 gives an 

 analysis of human sebum. 



In studies of the sebaceous secretion of the human subject, MacKenna 



