Human stratified squamous epithelia differ in cellular fatty acid composition

The phospholipid component of the cellular membrane is crucial to the structure and function of cells. Basal cells from three epithelial tissues, adult human skin epidermis, oral mucosa, and hair follicles, grow rapidly in serum- and lipid-free medium. Analysis of phospholipid extracts from the above three types of stratified squamous epithelium in both in vivo and in vitro was done to relate fatty acid cell composition to cell function. The fatty acid composition of hair follicles in vivo was analyzed in plucked scalp hairs, and those of skin epidermis and oral mucosa in vivo were analyzed after separating the tissue into suprabasal and basal layers. The fatty acid composition of the in vivo cells from hair follicles shows a partial essential fatty acid (EFA)-deficient state. There was no significant difference between the skin epidermis and the oral mucosa in the fatty acid composition of the in vivo cells from each basal layer. However, in the suprabasal layers, the percent of linoleic acid (18:2) from the skin epidermis was higher than that from the oral mucosa. This study shows that total fatty acid composition in cell membranes of stratified squamous epithelium varies with their keratinization pattern. When cultured, the three types of rapidly growing keratinocytes showed the same essential fatty acid deficient pattern in the membrane phospholipids.