Flux of fatty acids during epidermal differentiation.

Fetal rat skin prior to cornification (18 days of gestation) was prelabeled with [14C] linoleic acid in vitro and subsequently allowed to differentiate and cornify in organ culture. During 48 hr in culture total epidermal 14C fatty acids and 14C dienes decreased in phospholipids and increased in triglycerides and sterol esters as granular layers and stratum corneum formed. During the second 24-hr period, there was no net loss in 14C fatty acids from the epidermis, suggesting that the changes in phospholipid and neutral esters represented translocations of fatty acids within the cornifying cells. The findings are consistent with the hypothesis that fatty acids liberated by hydrolysis of phospholipids are salvaged by reesterfication as neutral lipid esters during epidermal cornification.