LIPIDS PRESENT IN SKIN AND ITS APPENDAGES 781 



myristyl alcohol (n-tetradecanol) and lauryl alcohol (n-dodecanol) also 

 appears probable. 



The wax fraction can be divided into two distinct types. One group, 

 present in a large amount in the epidermal region, consists of esters of 

 aliphatic alcohols with a saturated hydroxy acid. The second group is 

 made, up of cholesterol combined with unsaturated acids. 



The site of formation of the epidermal wax is uncertain. Because of the 

 saturated nature of the wax, it was first thought to be formed as a result 

 of oxidation processes occurring at the epidermal surface. However, the 

 results of Koppenhoefer, 403 which indicated the presence of only 30% of the 

 total wax in the horn division as contrasted with 65% of the total in the 

 lower basal region, would seem to refute this earlier hypothesis. The 

 best suggestion as to the site of origin of the epidermal wax is that it is 

 formed in the sebaceous secretion. 



d. Triglycerides in the Corium. Although neutral fats are practically 

 absent from the outer skin layers, appreciable amounts are present in the 

 corium, where they occur as cellular deposits distributed among and be- 

 tween the corium fiber elements. 403 The deposition of fat is more pro- 

 nounced along the subcutaneous border, and is identical in histologic 

 structure with that in the cells of this layer. 421 The amount of the fat 

 deposits in the corium region varies considerably from skin to skin, prob- 

 ably depending upon the nutritional status of the animal from which the 

 skin was obtained. The corium triglycerides are made up of approxi- 

 mately 65% liquid and 35% solid fatty acids. Tripalmitin has been iso- 

 lated from the corium lipids. 402 



e. Free Fatty Acids in the Skin. Free fatty acids were shown by Eng- 

 man and Kooyman 405 to be present in a considerable concentration on the 

 surface of the human skin. This worker attributed his finding to the lipo- 

 lytic action of bacteria and enzymes, followed by an atmospheric oxidation 

 at the skin surface. According to the results of Koppenhoefer, 403 there 

 was a progressive increase in the free fatty acids as one approached the 

 outer surface of the skin regions. The origin of the free acids appears to be 

 in doubt. Although the fatty acids of the horn division resembled those 

 of the phospholipids, except that the free fatty acids had a higher acetyl 

 value, the composition of the free fatty acids of the basal region differed 

 markedly from that of the combined acids. 



De Boer 216 reported that chronic dehydration of the dog, produced by 

 withholding food and water, resulted in a 4% decrease in the fat in the skin. 



42i F O'Flaherty and W. T. Roddy, J. Am, Leather Chem. Assoc, SO, 290-311 (1935). 



