Composition and morphology of epidermal cyst lipids.
The contents of epidermal cysts were used as a source of desquamated human keratinocytes uncontaminated by sebaceous, subcutaneous, or bacterial lipids. Lipids extracted with chloroform:methanol mixtures included six series of ceramides (41% of the total extractable lipid), cholesterol (27%), cholesteryl esters (10%), fatty acids (9%), cholesteryl sulfate (1.9%), a novel class of ceramide esters (3.8%), and a sterol diester (0.9%). Electron microscopy revealed that the lipids in the cyst contents existed as multiple intercellular lamellae, as in stratum corneum. One lamella, adjacent to the horny cell protein envelope, was resistant to lipid extraction and is thought to represent covalently bound lipid on the outer surface of the keratinocyte. The results indicate that the degradation of intercellular lipid lamellae is not required for desquamation.
Wertz
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PW
Marshall Dermatology Research Laboratories, Department of Dermatology, University of Iowa College of Medicine, Iowa City 52242.
Swartzendruber
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DC
Madison
K C
KC
Downing
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DT
D002518:Ceramides / Q000032:analysis; D002784:Cholesterol / Q000032:analysis; D004814:Epidermal Cyst / Q000032:analysis* / Q000648:ultrastructure; D004952:Esters / Q000032:analysis; D005227:Fatty Acids / Q000032:analysis; D006801:Humans; D008055:Lipids / Q000032:analysis*; D008854:Microscopy, Electron; D013256:Steroids / Q000032:analysis
D002518:Ceramides; D004952:Esters; D005227:Fatty Acids; D008055:Lipids; D013256:Steroids; D002784:Cholesterol